U.S. patent application number 11/050587 was filed with the patent office on 2005-06-23 for optical recording method and optical recording device.
This patent application is currently assigned to Sharp Kabushiki Kaisha. Invention is credited to Adachi, Yoshihisa.
Application Number | 20050135212 11/050587 |
Document ID | / |
Family ID | 26571244 |
Filed Date | 2005-06-23 |
United States Patent
Application |
20050135212 |
Kind Code |
A1 |
Adachi, Yoshihisa |
June 23, 2005 |
Optical recording method and optical recording device
Abstract
A reverse pattern is formed in a track adjacent to a specified
track on an optical recording medium with a predetermined light
beam capable of writing large recording marks. Thereafter, a normal
pattern is formed in an area, of an adjacent track, which is
adjacent to the reverse pattern in the specified track with
recording light beams of various strengths, the adjacent track
being adjacent to the specified track. The specified track is read
to detect a plurality of read-out signals according to individual
light beam conditions. The adjacent track is read to detect a
plurality of read-out signals according to individual light beam
conditions. An optimum recording condition is determined for the
specified track from the plurality of light beam condition and the
read-out signals from the specified track and the adjacent track,
and information is recorded in the specified track according to the
optimum recording condition. Thus, even when there exists a
difference in recording sensitivity between adjacent tracks, since
the width of the recording marks can be controlled to be optimum,
cross-talk between tracks during signal reproduction and
cross-erase during signal recording are restrained to minimum
levels, and recording density is improved.
Inventors: |
Adachi, Yoshihisa;
(Tenri-shi, JP) |
Correspondence
Address: |
EDWARDS & ANGELL, LLP
P.O. BOX 55874
BOSTON
MA
02205
US
|
Assignee: |
Sharp Kabushiki Kaisha
|
Family ID: |
26571244 |
Appl. No.: |
11/050587 |
Filed: |
February 2, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11050587 |
Feb 2, 2005 |
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09712765 |
Nov 14, 2000 |
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6876611 |
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Current U.S.
Class: |
369/47.53 |
Current CPC
Class: |
G11B 7/00718 20130101;
G11B 11/10595 20130101; G11B 11/1053 20130101; G11B 7/1267
20130101 |
Class at
Publication: |
369/047.53 |
International
Class: |
G11B 005/09 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 15, 1999 |
JP |
11-323596 |
Oct 3, 2000 |
JP |
2000-303158 |
Claims
1-6. (canceled)
7. An optical recording method of recording information on an
optical recording medium, comprising the steps of: (a) recording a
first test pattern in a first track on the optical recording medium
under such a predetermined recording condition to form a wider
recording mark than the first track; (b) after the recording of the
first test pattern, recording a second test pattern in an area, of
a second track, which is adjacent to a recording area of the first
test pattern under a plurality of recording conditions, the second
track being adjacent to the first track; (c) reading the second
track to detect a second read-out signal according to each of the
plurality of recording conditions; (d) obtaining a second recording
condition under which the second read-out signal attains a
predetermined state and performing a calculation on the second
recording condition, so as to obtain a recording condition under
which a wider recording mark is formed than under the second
recording condition and designate this recording condition as an
optimum recording condition; and (e) recording information in the
second track under the optimum recording condition.
8. The optical recording method as defined in claim 7, wherein: an
amplitude of the second read-out signal is detected in step (c);
and a recording condition under which the amplitude of the second
read-out signal reaches a predetermined value is obtained in step
(d) as a second recording condition.
9. The optical recording method as defined in claim 7, wherein: a
jitter of the second read-out signal detected in step (c); and a
recording condition under which the jitter of the second read-out
signal reaches a predetermined value is obtained in step (d) as a
second recording condition.
10. The optical recording method as defined in claim 7, wherein an
error rate of the second read-out signal detected in step (c); and
a recording condition under which the error rate of the second
read-out signal reaches a predetermined value is obtained in step
(d) as a second recording condition.
11. An optical recording method of recording information on an
optical recording medium, comprising the steps of: (a) recording a
first test pattern in a first track on the optical recording medium
under such a predetermined recording condition to form a wider
recording mark than the first track; (b) after the recording of the
first test pattern, recording a second test pattern in an area, of
a second track, which is adjacent to a recording area of the first
test pattern under a plurality of recording conditions, the second
track being adjacent to the first track; (c) reading the first
track to detect a first read-out signal according to each of the
plurality of recording conditions; (d) obtaining a first recording
condition under which the first read-out signal attains a
predetermined state and performing a calculation on the first
recording condition, so as to obtain a recording condition under
which a narrower recording mark is formed than under the first
recording condition and designate this recording condition as an
optimum recording condition; and (e) recording information in the
second track under the optimum recording condition.
12. The optical recording method as defined in claim 11, wherein:
an amplitude of the first read-out signal is detected in step (c);
a recording condition under which the amplitude of the first
read-out signal reaches a predetermined value is obtained in step
(d) as a first recording condition.
13. The optical recording method as defined in claim 11, wherein: a
jitter of the first read-out signal detected in step (c); and a
recording condition under which the jitter of the first read-out
signal reaches a predetermined value is obtained in step (d) as a
first recording condition.
14. The optical recording method as defined in claim 11, wherein an
error rate of the first read-out signal detected in step (c); and a
recording condition under which the error rate of the first
read-out signal reaches a predetermined value is obtained in step
(d) as a first recording condition.
15. (canceled)
16. An optical recording device for recording information on an
optical recording medium by at least projecting a light beam
thereon comprising: recording means for recording a first test
pattern in a first track on the optical recording medium under such
a predetermined recording condition to form a wider recording mark
than the first track in determining a recording condition for a
second track and also for recording, after the recording of the
first test pattern, a second test pattern in an area, of a second
track, which is adjacent to a recording area of the first test
pattern under a plurality of recording conditions, the second track
being adiacent to the first track; read-out means for reading the
first track to detect a first read-out signal according to each of
the plurality of recording conditions and also for reading the
second track to detect a second read-out signal according to each
of the plurality of recording conditions; and optimum recording
condition determining means for determining an optimum recording
condition for the second track from the plurality of recording
conditions and the first and second read-out signals, wherein: if
the first read-out signal does not attain a predetermined state,
the optimum recording condition determining means obtains a second
recording condition under which the second read-out signal attains
a predetermined state and perform a calculation on the second
recording condition, so as to obtain a recording condition under
which a wider recording mark is formed than under the second
recording condition and designate this recording condition as an
optimum recording condition.
17. An optical recording device for recording information on an
optical recording medium by at least projecting a light beam
thereon, comprising: recording means for recording a first test
pattern in a first track on the optical recording medium under such
a predetermined recording condition to form a wider recording mark
than the first track in determining a recording, condition for a
second track and also for recording, after the recording of the
first test pattern, a second test pattern in an area, of a second
track, which is adjacent to a recording area of the first test
pattern under a plurality of recording conditions, the second track
being adjacent to the first track: read-out means for reading the
first track to detect a first read-out signal according to each of
the plurality of recording conditions and also for reading the
second track to detect a second read-out signal according to each
of the plurality of recording conditions; and optimum recording
condition determining means for determining an optimum recording
condition for the second track from the plurality of recording
conditions and the first and second read-out signals, wherein: the
optimum recording condition determining means evaluates whether an
amplitude of the first read-out signal has reached a predetermined
threshold value; if the amplitude of the first read-out signal has
reached the threshold value, the optimum recording condition
determining means determines an optimum recording condition based
on the plurality of recording conditions and the amplitudes of the
first and second read-out signals; and if the amplitude of the
first read-out signal has not reached the threshold value, the
optimum recording condition determining means obtains a second
recording condition under which an amplitude of the second read-out
signal reaches a predetermined value and performs a calculation on
the second recording condition, so as to obtain a recording
condition under which a wider recording mark is formed than under
the second recording condition and designate this recording
condition as an optimum recording condition.
18. An optical recording device for recording information on an
optical recording medium by at least projecting a light beam
thereon, comprising: recording means for recording a first test
pattern in a first track on the optical recording medium under such
a predetermined recording condition to form a wider recording mark
than the first track in determining a recording condition for a
second track and also for recording, after the recording of the
first test pattern, a second test pattern in an area of a second
track, which is adjacent to a recording area of the first test
pattern under a plurality of recording conditions, the second track
being adjacent to the first track; read-out means for reading the
first track to detect a first read-out signal according to each of
the plurality of recording conditions and also for reading the
second track to detect a second read-out signal according to each
of the plurality of recording conditions; optimum recording
condition determining means for determining an optimum recording
condition for the second track from the plurality of recording
conditions and the first and second read-out signals; and
normalizing means for normalizing at least either one of quantities
derived from the first and second read-out signals by the read-out
means, so as to correct a difference in sensitivity between
individual tracks.
19. An optical recording device for recording information on an
optical recording medium by at least projecting a light beam
thereon, comprising: recording means for recording a first test
pattern in a first track on the optical recording medium under such
a predetermined recording condition to form a wider recording mark
than the first track in determining a recording condition for a
second track and also for recording, after the recording of the
first test pattern, a second test pattern in an area of a second
track, which is adjacent to a recording area of the first test
pattern under a plurality of recording conditions, the second track
being adjacent to the first track; read-out means for reading the
first track to detect a first read-out signal according to each of
the plurality of recording conditions and also for reading the
second track to detect a second read-out signal according to each
of the plurality of recording conditions; optimum recording
condition determining means for determining an optimum recording
condition for the second track from the plurality of recording
conditions and the first and second read-out signals; and
normalizing means for normalizing at least either one of signal
quantities derived from the first and second read-out signals by
the read-out means using a maximum values of amplitudes of the
first and second read-out signals.
20. An optical recording device for recording information on an
optical recording medium by at least projecting a light beam
thereon, comprising: recording means for recording a first test
pattern in a first track on the optical recording medium under such
a predetermined recording condition to form a wider recording mark
than the first track in determining a recording condition for a
second track and also for recording, after the recording of the
first test pattern, a second test pattern in an area, of a second
track, which is adjacent to a recording area of the first test
pattern under a plurality of recording conditions, the second track
being adjacent to the first track; read-out means for reading the
first track to detect a first read-out signal according to each of
the plurality of recording conditions and also for reading the
second track to detect a second read-out signal according to each
of the plurality of recording conditions; optimum recording
condition determining means for determining an optimum recording
condition for the second track from the plurality of recording
conditions and the first and second read-out signals; and
circumferential variation normalizing means for normalizing at
least either one of quantities derived from the first and second
read-out signals by the read-out means, so as to correct a
variation in a circumferential direction.
21. (canceled)
22. An optical recording device for recording information on an
optical recording medium by at least projecting a light beam
thereon, comprising: recording means for recording a first test
pattern in a first track on the optical recording medium under such
a predetermined recording condition to form a wider recording mark
than the first track in determining a recording condition for a
second track and also for recording, after the recording of the
first test pattern, a second test pattern in an area, of a second
track, which is adjacent to a recording area of the first test
pattern under a plurality of recording conditions, the second track
being adjacent to the first track; read-out means for reading the
first track to detect a first read-out signal according to each of
the plurality of recording conditions and also for reading the
second track to detect a second read-out signal according to each
of the plurality of recording conditions; and optimum recording
condition determining means for determining an optimum recording
condition for the second track from the plurality of recording
conditions and the first and second read-out signals, wherein: the
first and second test patterns are constituted by a combined
pattern of marks and empty spaces, the marks and empty spaces being
longer than 2 T (T: channel bit length), and the optical recording
device further comprising: displacement correction means for
correcting recording positions of the first and second test
patterns recorded by the recording means so that marks are aligned
to marks or empty spaces along the direction perpendicular to the
tracks.
23. The optical recording device as defined in claim 22, wherein:
the recording means records a third test pattern in the second
track before recording the second test pattern; and the
displacement correction means corrects recording positions of the
first and third test patterns so that marks are aligned to marks or
empty spaces along the direction perpendicular to the tracks.
24. The optical recording device as defined in claim 23, wherein:
the third test pattern is identical to the first test pattern.
25. An optical recording device for recording information on an
optical recording medium by at least projecting a light beam
thereon, comprising: recording means for recording a first test
pattern in a first track on the optical recording medium under such
a predetermined recording condition to form a wider recording mark
than the first track in determining a recording condition for a
second track and also for recording, after the recording of the
first test pattern, a second test pattern in an area, of a second
track, which is adjacent to a recording area of the first test
pattern under a plurality of recording conditions, the second track
being adjacent to the first track; read-out means for reading the
first track to detect a first read-out signal according to each of
the plurality of recording conditions and also for reading the
second track to detect a second read-out signal according to each
of the plurality of recording conditions; and optimum recording
condition determining means for determining an optimum recording
condition for the second track from the plurality of recording
conditions and the first and second read-out signals, wherein: the
first and second test patterns are constituted by a combined
pattern of marks and empty spaces, the marks and empty spaces being
longer than (2+L).multidot.T, where T is a channel bit length and L
is a channel bit value required to prevent the recording means from
being adversely affected by displacement of a recording bit when a
recording condition is such that the second test pattern can be
recorded.
26-29. (canceled)
30. An optical recording device for recording information on an
optical recording medium by at least projecting a light beam
thereon, comprising: recording means for recording a first test
pattern in a first track on the optical recording medium under such
a predetermined recording condition to form a wider recording mark
than the first track in determining a recording condition for a
second track and also for recording, after the recording of the
first test pattern, a second test pattern in an area, of a second
track, which is adjacent to a recording area of the first test
pattern under a plurality of recording conditions, the second track
being adjacent to the first track; read-out means for reading the
second track to detect a second read-out signal according to each
of the plurality of recording conditions; and optimum recording
condition determining means for obtaining a second recording
condition under which the second read-out signal attains a
predetermined state and performing a calculation on the second
recording condition, so as to obtain a recording condition under
which a wider recording mark is formed than under the second
recording condition and designate this recording condition as an
optimum recording condition.
31. The optical recording device as defined in claim 30, wherein:
the read-out means detects an amplitude of the second read-out
signal; and the optimum recording condition determining means
obtains a recording condition under which an amplitude of the
second read-out signal reaches a predetermined value as a second
recording condition.
32. The optical recording device as defined in claim 30, further
comprising: normalizing means for normalizing a quantity derived
from the second read-out signal by the read-out means, so as to
correct a difference in sensitivity between individual tracks.
33. The optical recording device as defined in claim 31, further
comprising: normalizing means for normalizing a signal quantity
derived from the second read-out signal by the read-out means using
a maximum value of an amplitude of the second read-out signal.
34. The optical recording device as defined in claim 30, further
comprising: circumferential variation normalizing means for
normalizing a quantity derived from the second read-out signal by
the read-out means, so as to correct a variation in a
circumferential direction.
35. The optical recording device as defined in claim 31, further
comprising: circumferential variation normalizing means for causing
the read-out means to read the first track and detect a
circumferential variation normalization signal after the recording
means has recorded the first test pattern and before the recording
means records the second test pattern and for normalizing at least
either one of amplitudes of the first and second read-out signals
using an amplitude of the circumferential variation normalization
signal.
36. The optical recording device as defined in claim 30, wherein:
the second test pattern recorded by the recording means is
constituted by a reverse pattern of the first test pattern.
37. The optical recording device as defined in claim 31, further
comprising circumferential variation normalizing means for causing
the recording means to record a third test pattern before the
recording means records the second test pattern, for causing the
read-out means to read at least either one of the first and second
tracks and to detect a circumferential variation normalization
signal before the recording means records the second test pattern,
and for normalizing at least either one of the amplitudes of the
first and second read-out signals using an amplitude of the
circumferential variation normalization signal.
38. The optical recording device as defined in claim 37, wherein:
the third test pattern is identical to the first test pattern.
39. The optical recording device as defined in claim 30, wherein:
the first and second test patterns are constituted by a combined
pattern of marks and empty spaces, the marks and empty spaces being
longer than 2 T (T: channel bit length); and the optical recording
device further comprising: displacement correction means for
correcting recording positions of the first and second test
patterns recorded by the recording means so that marks are aligned
to marks or empty spaces along the direction perpendicular to the
tracks.
40. The optical recording device as defined in claim 39, wherein:
the recording means records a third test pattern in the second
track before recording the second test pattern; and the
displacement correction means corrects recording positions of the
first and third test patterns so that marks are aligned to marks or
empty spaces along the direction perpendicular to the tracks.
41. The optical recording device as defined in claim 40, wherein:
the third test pattern is identical to the first test pattern.
42. The optical recording device as defined in claim 30, wherein:
the first and second test patterns are constituted by a combined
pattern of marks and empty spaces, the marks and empty spaces being
longer than (2+L).multidot.T, where T is a channel bit length and L
is a channel bit value required to prevent the recording means from
being adversely affected by displacement of a recording bit when a
recording condition is such that the second test pattern can be
recorded.
43. The optical recording device as defined in claim 30, wherein:
the first track is formed in either one of a land or a groove; and
the second track is formed in the other.
44. The optical recording device as defined in claim 30, wherein:
the read-out means detects a jitter of the second read-out signal;
and the optimum recording condition determining means obtains a
recording condition under which the jitter of the second read-out
signal reaches a predetermined value as a second recording
condition.
45. The optical recording device as defined in claim 30, wherein:
the read-out means detects an error rate of the second read-out
signal; and the optimum recording condition determining means
obtains a recording condition under which the error rate of the
second read-out signal reaches a predetermined value as a second
recording condition
46. An optical recording device for recording information on an
optical recording medium by at least projecting a light beam
thereon, comprising: recording means for recording a first test
pattern in a first track on the optical recording medium under such
a predetermined recording condition to form a wider recording mark
than the first track in determining a recording condition for a
second track and also for recording, after the recording of the
first test pattern, a second test pattern in an area, of a second
track, which is adjacent to a recording area of the first test
pattern under a plurality of recording conditions, the second track
being adjacent to the first track; read-out means for reading the
first track to detect a first read-out signal according to each of
the plurality of recording conditions; and optimum recording
condition determining means for obtaining a first recording
condition under which the first read-out signal attains a
predetermined state and performing a calculation on the first
recording condition, so as to obtain a recording condition under
which a narrower recording mark is formed than under the first
recording condition and designate this recording condition as an
optimum recording condition.
47. The optical recording device as defined in claim 46, wherein:
the read-out means detects an amplitude of the first read-out
signal; and the optimum recording condition determining means
obtains a recording condition under which the amplitude of the
first read-out signal reaches a predetermined value as a first
recording condition.
48. The optical recording device as defined in claim 46, further
comprising: normalizing means for normalizing a quantity derived
from the first read-out signal by the read-out means, so as to
correct a difference in sensitivity between individual tracks.
49. The optical recording device as defined in claim 47, further
comprising: normalizing means for normalizing a signal quantity
derived from the first read-out signal by the read-out means using
a maximum value of an amplitude of the first read-out signal.
50. The optical recording device as defined in claim 46, further
comprising: circumferential variation normalizing means for
normalizing a quantity derived from the first read-out signal by
the read-out means, so as to correct a variation in a
circumferential direction.
51. The optical recording device as defined in claim 47, further
comprising: circumferential variation normalizing means for causing
the read-out means to read the first track and detect a
circumferential variation normalization signal after the recording
means has recorded the first test pattern and before the recording
means records the second test pattern and for normalizing at least
either one of amplitudes of the first and second read-out signals
using an amplitude of the circumferential variation normalization
signal.
52. The optical recording device as defined in claim 46, wherein:
the second test pattern recorded by the recording means is
constituted by a reverse pattern of the first test pattern.
53. The optical recording device as defined in claim 47, further
comprising: circumferential variation normalizing means for causing
the recording means to record a third test pattern before the
recording means records the second test pattern, for causing the
read-out means to read at least either one of the first and second
tracks and to detect a circumferential variation normalization
signal before the recording means records the second test pattern,
and for normalizing at least either one of the amplitudes of the
first and second read-out signals using an amplitude of the
circumferential variation normalization signal. C
54. The optical recording device as defined in claim 53, wherein:
the third test pattern is identical to the first test pattern.
55. The optical recording device as defined in claim 46, wherein:
the first and second test patterns are constituted by a combined
pattern of marks and empty spaces, the marks and empty spaces being
longer than 2 T (T: channel bit length); and the optical recording
device further comprising: displacement correction means for
correcting recording positions of the first and second test
patterns recorded by the recording means so that marks are aligned
to marks or empty spaces along the direction perpendicular to the
tracks.
56. The optical recording device as defined in claim 55, wherein:
the recording means records a third test pattern in the second
track before recording the second test pattern; and the
displacement correction means corrects recording positions of the
first and third test patterns so that marks are aligned to marks or
empty spaces along the direction perpendicular to the tracks.
57. The optical recording device as defined in claim 56, wherein:
the third test pattern is identical to the first test pattern.
58. The optical recording device as defined in claim 46, wherein:
the first and second test patterns are constituted by a combined
pattern of marks and empty spaces, the marks and empty spaces being
longer than (2+L).multidot.T, where T is a channel bit length and L
is a channel bit value required to prevent the recording means from
being adversely affected by displacement of a recording bit when a
recording condition is such that the second test pattern can be
recorded.
59. The optical recording device as defined in claim 46, wherein:
the first track is formed in either one of a land or a groove; and
the second track is formed in the other.
60. The optical recording device as defined in claim 46, wherein:
the read-out means detects a jitter of the first read-out signal;
and the optimum recording condition determining means obtains a
recording condition under which the jitter of the first read-out
signal reaches a predetermined value as a first recording
condition
61. The optical recording device as defined in claim 46, wherein:
the read-out means detects an error rate of the first read-out
signal; and the optimum recording condition determining means
obtains a recording condition under which the error rate of the
first read-out signal reaches a predetermined value as a first
recording condition.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to optical recording methods
and optical recording devices to record information on optical
recording media, in particular, to optical recording methods and
optical recording devices capable of optimizing a recording
condition.
BACKGROUND OF THE INVENTION
[0002] In recent years, researches have been conducted with
increasing vigor to achieve an improved level of high density
recording with optical disks. One of obstacles in doing so is that
when a recording condition, such as the quantity of a recording
light beam projected on the optical disk or the strength of a
recording magnetic field externally applied on the magneto-optical
disk, changes, the resultant recording marks vary in width (a size
measured perpendicular to the track), which obstructs uniform
recording and makes it difficult to effect high density
recording.
[0003] A solution to this problem is disclosed in Japanese
Laid-Open Patent Application No. 11-73700/1999 (Tokukaihei
11-73700; published on Mar. 16, 1999; corresponding to U.S. Pat.
No. 6,125,085) whereby the quantity of recording light and the
strength of a recording magnetic field are controlled. According to
this method, a first test pattern is recorded in a specified track
(a track where the recording power is to be optimized), before a
second test pattern is recorded in an adjacent track using the same
quantity of recording light or the same strength of a recording
magnetic field as in the recording of the first test pattern. The
first pattern recorded in the specified track is then reproduced.
The reproduction signal has an amplitude level reflecting
cross-talk during reproduction and cross-erase from adjacent
tracks. Therefore, an optimum quantity of recording light or
strength of a recording magnetic field can be specified based on
the amplitude level of the reproduction signal.
[0004] Japanese Laid-Open Patent Application No. 10-69639/1998
(Tokukaihei 10-69639; published on Mar. 10, 1998) discloses a
method of recording information in both the land and the groove.
According to the disclosure, information is erased in a
predetermined track and its adjacent tracks on an optical recording
medium. Then, predetermined information is recorded in these
adjacent tracks with various recording powers. Subsequently,
information in the predetermined track is reproduced to detect the
levels of reproduction signals. The levels of reproduction signals
are matched to respective recording powers. The recording power at
which the level of the reproduction signal shows a sharp increase
is designated as the optimum recording power for the predetermined
track.
[0005] Japanese Laid-Open Patent Application No. 10-69639/1998
describes in its fifth embodiment, paragraphs [0071] to [0073], how
to find out the optimum recording power in-both the land and the
groove. For example, to obtain a recording power for the land, a
signal is recorded in the groove followed by replay of the land to
find out a recording power at which the levels of the reproduction
signal shows a sharp increase and designate that recording power as
the optimum recording power for the land.
[0006] However, according to the method disclosed in Japanese
Laid-Open Patent Application No. 11-73700/1999 mentioned above, to
find the optimum quantity of recording light and strength of a
recording magnetic field for the specified track, cross-talk is
used which occurs during reproduction in the specified track (the
track where the recording power is to be optimized). This shows how
the specified track is affected by the recording in the adjacent
tracks, not how the adjacent tracks are affected by the recording
in the specified track.
[0007] Therefore, if recording sensitivity differs between the
specified track and its adjacent tracks, the method fails and it
becomes impossible to optimize the quantity of recording light and
strength of a recording magnetic field.
[0008] The same problem exists in the method disclosed in Japanese
Laid-Open Patent Application No. 10-69639/1998: it is detected
through reproduction in the specified track how the specified track
(the track where the recording power is to be optimized) is
affected by the recording in the adjacent tracks, and the results
will be used to obtain an optimum recording power for the specified
track. Accordingly, if recording sensitivity differs between the
specified track and its adjacent tracks, the method fails and it
becomes impossible to optimize the quantity of recording light and
strength of a recording magnetic field.
SUMMARY OF THE INVENTION
[0009] The present invention addresses the aforementioned problem
and has an objective to offer an optical recording method and
device which, even if recording sensitivity differs between
adjacent tracks, is capable of controlling the width of the
recording mark to be optimum, minimizing cross-talk between tracks
during reproduction of a signal and cross-erase during recording of
a signal (a phenomenon in which an edge of a recording mark is
erased by the recording light that spills over from an adjacent
track)., and achieving an improved level of high density track
recording.
[0010] To accomplish the-above objective, a first optical recording
method in accordance with the present invention is an optical
recording method of recording information on an optical recording
medium and is characterized in that the method includes the steps
of:
[0011] (a) recording a first test pattern in a first track on the
optical recording medium under such a predetermined recording
condition to form a wider recording mark than the first track;
[0012] (b) after the recording of the first test pattern, recording
a second test pattern in an area, of a second track, which is
adjacent to a recording area of the first test pattern under a
plurality of recording conditions, the second track being adjacent
to the first track;
[0013] (c) reading the first track to detect a first read-out
signal according to each of the plurality of recording
conditions;
[0014] (d) reading the second track- to detect a second read-out
signal according to each of the plurality of recording
conditions;
[0015] (e) determining an optimum recording condition for the
second track from the plurality of recording conditions and the
first and second read-out signals; and
[0016] (f) recording information in the second track under the
optimum recording condition.
[0017] To accomplish the above objective, a first optical recording
device in accordance with the present invention is an optical
recording device for recording information on an optical recording
medium by at least projecting a light beam thereon and is
characterized in that the device includes:
[0018] recording means for recording a first test pattern in a
first track on the optical recording medium under such a
predetermined recording condition to form a wider recording mark
than the first track in determining a recording condition for a
second track and also for recording, after the recording of the
first test pattern, a second test pattern in an area, of a second
track, which is adjacent to a recording area of the first test
pattern under a plurality of recording conditions, the second track
being adjacent to the first track;
[0019] read-out means for reading the first track to detect a first
read-out signal according to each of the plurality of recording
conditions and also for reading the second track to detect a second
read-out signal according to each of the plurality of recording
conditions; and
[0020] optimum recording condition determining means for
determining an optimum recording condition for the second track
from the plurality of recording conditions and the first and second
read-out signals.
[0021] With this first optical recording method and device, prior
to recording information in the second track, a first test pattern
is recorded in a first track under such a predetermined recording
condition to form a wider recording mark than the first track, then
a second test pattern is recorded in a second track under a
plurality of recording conditions, and an optimum recording
condition is determined for the second track based on the plurality
of conditions, the second read-out signal detected from the second
track, and the first read-out signal detected from the first
track.
[0022] Thus, a condition to produce a sufficient reproduction
signal becomes obtainable from the second read-out signal detected
from the second track, and a condition to prevent cross-erase
becomes obtainable from the first read-out signal detected from the
first track. An optimum recording condition satisfying these
conditions is determined for the second track. Thus, even when
there occurs a difference in recording sensitivity between the
first and second tracks, the recording condition for the second
track can be suitably determined. Therefore, cross-talk between
tracks during signal reproduction and cross-erase during signal
recording are restrained to minimum levels, and recording density
is improved.
[0023] A second optical recording method in accordance with the
present invention is an optical recording method of recording
information on an optical recording medium and is characterized in
that the method includes the steps of:
[0024] (a) recording a first test pattern in a first track on the
optical recording medium under such a predetermined recording
condition to form a wider recording mark than the first track;
[0025] (b) after the recording of the first test pattern, recording
a second test pattern in an area, of a second track, which is
adjacent to a recording area of the first test pattern under a
plurality of recording conditions, the second track being adjacent
to the first track;
[0026] (c) reading the second track to detect a second read-out
signal according to each of the plurality of recording
conditions;
[0027] (d) obtaining a second recording condition under which the
second read-out signal attains a predetermined state and performing
a calculation on the second recording condition, so as to obtain a
recording condition under which a wider recording mark is formed
than under the second recording condition and designate this
recording condition as an optimum recording condition; and
[0028] (e) recording information in the second track under the
optimum recording condition.
[0029] A second optical recording device in accordance with the
present invention is an optical recording device for recording
information on an optical recording medium by at least projecting a
light beam thereon, and is characterized in that the device
includes:
[0030] recording means for recording a first test pattern in a
first track on the optical recording medium under such a
predetermined recording condition to form a wider recording mark
than the first track in determining a recording condition for a
second track and also for recording, after the recording of the
first test pattern, a second test pattern in an area, of a second
track, which is adjacent to a recording area of the first test
pattern under a plurality of recording conditions, the second track
being adjacent to the first track;
[0031] read-out means for reading the second track to detect a
second read-out signal according to each of the plurality of
recording conditions; and
[0032] optimum recording condition determining means for obtaining
a second recording condition under which the second read-out signal
attains a predetermined state and performing a calculation on the
second recording condition, so as to obtain a recording condition
under which a wider recording mark is formed than under the second
recording condition and designate this recording condition as an
optimum recording condition.
[0033] With this second optical recording method and device, prior
to recording information in the second track, a first test pattern
is recorded in a first track under such a predetermined recording
condition to form a wider recording mark than the first track, then
a second test pattern is recorded in a second track under a
plurality of recording conditions, and a recording condition under
which wider recording marks are formed than under the second
recording condition is obtained by performing a calculation on the
second recording condition under which the second read-out signal
detected from the second track attains a predetermined state. This
recording condition is then designated as an optimum recording
condition for the second track. Thus, a recording condition under
which a sufficient reproduction signal is obtained from the second
track can be designated as an optimum recording condition for the
second track.
[0034] A third optical recording method in accordance with the
present invention is an optical recording method of recording
information on an optical recording medium and is characterized in
that the method includes the steps of:
[0035] (a) recording a first test pattern in a first track on the
optical recording medium under such a predetermined recording
condition to form a wider recording mark than the first track;
[0036] (b) after the recording of the first test pattern, recording
a second test pattern in an area, of a second track, which is
adjacent to a recording area of the first test pattern under a
plurality of recording conditions, the second track being adjacent
to the first track;
[0037] (c) reading the first track to detect a first read-out
signal according to each of the plurality of recording
conditions;
[0038] (d) obtaining a first recording condition under which the
first read-out signal attains a predetermined state and performing
a calculation on the first recording condition, so as to obtain a
recording condition under which a narrower recording mark is formed
than under the first recording condition and designate this
recording condition as an optimum recording condition; and
[0039] (e) recording information in the second track under the
optimum recording condition.
[0040] A third optical recording device in accordance with the
present invention is an optical recording device for recording
information on an optical recording medium by at least projecting a
light beam thereon and is characterized in that the device
includes:
[0041] recording means for recording a first test pattern in a
first track on the optical recording medium under such a
predetermined recording condition to form a wider recording mark
than the first track in determining a recording condition for a
second track and also for recording, after the recording of the
first test pattern, a second test pattern in an area, of a second
track, which is adjacent to a recording area of the first test
pattern under a plurality of recording conditions, the second track
being adjacent to the first track;
[0042] read-out means for reading the first track to detect a first
read-out signal according to each of the plurality of recording
conditions; and
[0043] optimum recording condition determining means for obtaining
a first recording condition under which the first read-out signal
attains a predetermined state and performing a calculation on the
first recording condition, so as to obtain a recording condition
under which a narrower recording mark is formed than under the
first recording condition and designate this recording condition as
an optimum recording condition.
[0044] With this third optical recording method and device, prior
to recording information in the second track, a first test pattern
is recorded in a first track under such a predetermined recording
condition to form a wider recording mark than the first track, then
a second test pattern is recorded in a second track under a
plurality of recording conditions, and a recording condition under
which narrower recording marks are formed than under the first
recording condition is obtained by performing a calculation on the
first recording condition under which the first read-out signal
detected from the first track attains a predetermined state. This
recording condition is then designated as an optimum recording
condition for the second track. Thus, a recording condition under
which the second track produces no cross-talk on the first track
can be designated as an optimum recording condition for the second
track.
[0045] For a fuller understanding of the nature and advantages of
the invention, reference should be made to the ensuing detailed
description taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] FIG. 1(a) to FIG. 1(d) are diagrams illustrating a method to
control a recording condition in accordance with embodiment 1.
[0047] FIG. 2 is a graph showing the amplitudes of read-out signals
from tracks Tr(n) and Tr(n+1) in accordance with embodiment 1.
[0048] FIG. 3 is a flow chart showing a method to control a
recording condition in accordance with embodiment 1.
[0049] FIG. 4 is a graph showing the amplitudes of read-out signals
from tracks Tr(n) and Tr(n+1) in accordance with embodiment 2.
[0050] FIG. 5 is a flow chart showing a method to control a
recording condition in accordance with embodiment 2.
[0051] FIG. 6(a) to FIG. 6(d) are diagrams illustrating a method to
control a recording condition in accordance with embodiment 3.
[0052] FIG. 7 is a graph showing the amplitudes of read-out signals
from tracks Tr(n) and Tr(n+1) in accordance with embodiment 3.
[0053] FIG. 8 is a graph showing the amplitudes of other read-out
signals from tracks Tr(n) and Tr(n+1) in accordance with embodiment
3.
[0054] FIG. 9 is a block diagram illustrating, as an example, a
configuration of a device which controls a recording condition in
accordance with the present invention.
[0055] FIG. 10(a) is a diagram illustrating a configuration of a
clock deriving circuit shown in FIG. 9.
[0056] FIG. 10(b) and FIG. 10(c) are waveform diagrams illustrating
an operation of the clock deriving circuit shown in FIG. 10(a).
[0057] FIG. 11 is a flow chart showing a method to control a
recording condition in accordance with embodiment 3.
[0058] FIG. 12 is a graph showing how the amplitudes of
reproduction signals change with the quantity of recording light
according to a conventional technology.
[0059] FIG. 13 is a graph showing recording positions which differ
between adjacent tracks.
[0060] FIG. 14(a) to FIG. 14(c) are diagrams illustrating a method
to control a recording condition in accordance with embodiment
4.
[0061] FIG. 15 is a graph showing the amplitudes V(n) of signals
reproduced in a track Tr(n) in accordance with embodiment 4.
[0062] FIG. 16 is a flow chart showing a method to control a
recording condition in accordance with embodiment 4.
[0063] FIG. 17 is a graph showing the normalized amplitudes V(n)
and V(n+1) of signals in accordance with embodiment 5.
[0064] FIG. 18 is a graph showing the dependence of the amplitude
V(n+1) of a signal on the quantity of recording light, illustrating
a method to control a recording condition in accordance with
embodiment 6.
[0065] FIG. 19(a) and FIG. 19(b) are graphs showing circumferential
variations in the tilt and the amplitude of a signal.
DESCRIPTION OF THE EMBODIMENTS
Embodiment 1
[0066] Taking magneto-optical recording methods and devices as
examples, the following description will discuss an embodiment of
the present invention in reference to FIG. 1(a) to FIG. 1(d), FIG.
2, and FIG. 3.
[0067] Here, magneto-optical recording is effected through
modulation of a magnetic field. There are various recording
conditions that should be optimized in magnetic-field-modulated
recording: namely, the quantity of recording light (the quantity of
a light beam projected on the optical recording medium during
recording), the strength of a recording magnetic field (the
strength of a magnetic field applied to the optical recording
medium during recording), etc. Among them, we will focus for
convenience in description on the quantity of recording light. As
to optimization of the strength of a recording magnetic field, a
similar description applies, so a brief explanation will be given
at the end. Accordingly, hereinafter, the strength of a recording
magnetic field is assumed to be constant, and the quantity of
recording light is varied to find out an optimum quantity of
recording light.
[0068] In the present invention, the width of a recording mark in a
specified track and the quantity of a read-out signal (reproduction
signal) from an adjacent track show the spillover effects produced
by the recording mark on the adjacent track. The width of a
recording mark in a specified track is optimized based on the
detected width of a recording mark and the detected quantity of the
read-out signal. From the optimum width, we can obtain an optimum
quantity of recording light by which information will be recorded
in the specified track. Ideally, the quantity of recording light is
optimized every time information is to be recorded. In actual use,
however, the optimization may be effected only when a recording
medium is inserted in the device.
[0069] Following the optimization of the quantity of recording
light, recording is effected according to a conventional,
well-known technique. In the description below, we therefore will
focus on methods and devices to optimize the quantity of light,
which forms the core feature of the present invention.
[0070] Further, although we will discuss in the following
description the optimization of the quantity of recording light for
a track Tr(n) among a plurality of tracks Tr on the magneto-optical
recording medium, the same description of course applies to every
one of the other tracks too. Ideally, the quantity of recording
light is optimized at least once for each track. In actual use
where information is recorded both in the lands and the grooves,
however, if the quantity of recording light is optimized at least
once for one of the lands and one-of the grooves, the optimization
does not have to be effected on the other tracks. The operation may
be effected on every group of tracks, for example.
[0071] Now, the optimization of the quantity of recording light,
which forms the core feature of the present embodiment, will be
discussed in terms of its principles.
[0072] First Step
[0073] As illustrated in FIG. 1(a), a light beam 1 is projected to
erase tracks Tr(n-1) and Tr(n+1) which are adjacent to a track
Tr(n) as a second track on which the optimization of the quantity
of light is to be effected. The quantity of the light beam 1 is set
to a relatively high value to erase data in an erasure area 2 of
which the width is greater than the track width. Here, we define
the term, "to erase tracks Tr(n-1) and Tr(n+1)", as encompassing
recording of an erasing pattern, as a first test pattern, in the
tracks Tr(n-1) and Tr(n+1).
[0074] In FIG. 1(a) to FIG. 1(d), in the case of recording in both
the land and the groove which is a well-known high density
recording method, the tracks Tr(n) and Tr(n+2) refer to grooves,
and the tracks Tr(n-1) and Tr(n+1) refer to lands, for example.
[0075] Second Step
[0076] Next, as illustrated in FIG. 1(b), recording marks 4 are
written to form a predetermined pattern in the tracks Tr(n) and
Tr(n+2) using a certain quantity of a light beam 3 (here, a
relatively small quantity of light), while applying a recording
magnetic field of which the polarity is being reversed. The
recording marks 4 have smaller widths (size measured perpendicular
to the track) than the track width.
[0077] Third Step
[0078] Subsequently, the track Tr(n) as a first track is replayed
to detect a read-out signal (second read-out signal) 5. Here, the
amplitude of the read-out signal 5 is detected. In FIG. 1(b), the
recording marks 4 have small widths, and accordingly the amplitude
V1 of the read-out signal 5 is small.
[0079] Fourth Step
[0080] In this step, the track Tr(n+1) is replayed to detect a
read-out signal (first read-out signal) 6. Here, the amplitude of
the read-out signal 6 is detected. In FIG. 1(b), the recording
marks 4 are never wider than the track and do not produce spillover
effects on adjacent tracks. The resultant read-out signal 6 has an
amplitude V2=0.
[0081] Fifth Step
[0082] The second to fourth steps are repeated with different
quantities of recording light in the second step. FIG. 1(c) shows
results of recording with an increased quantity of light (light
beam 7) compared to the case in FIG. 1(b). The edges of the
recording marks 8 are located very close to the edges of the track.
Under these circumstances, the amplitude V3 of a read-out signal 9
from the track Tr(n) is large, whereas the amplitude V4 of a
read-out signal 10 from the track Tr(n+1) remains 0 because the
recording marks 8 produce small spillover effects on the track
Tr(n+1). FIG. 1(d) shows results of recording with a further
increased quantity of light (light beam 11). The edges of the
widened recording marks 12 in the tracks Tr(n) and Tr(n+2) exist in
the adjacent track Tr(n+1). Accordingly, the amplitude V5 of the
signal 13 reproduced from the track Tr(n) is large, and the
amplitude V6 of the signal 14 reproduced from the track Tr(n+1) is
also large.
[0083] Sixth Step
[0084] Now, the read-out signals (to be more precise, the
amplitudes V(n) and V(n+1) of the signals) from the tracks Tr(n)
and Tr(n+1) are matched with the quantities of recording light.
[0085] FIG. 2 is drawn by plotting the amplitudes V(n) and V(n+1)
of the read-out signals reproduced respectively from the track
Tr(n) and its adjacent track Tr(n+1) against the quantities of
recording light, with recording marks being written in the tracks
Tr(n) and Tr(n+2) under a recording condition illustrated in FIG.
1(b) (condition (b)), that illustrated in FIG. 1(c) (condition
(c)), and that illustrated in FIG. 1(d) (condition (d)). When the
quantity of recording light is small (FIG. 1(b)), the amplitudes
V(n) and V(n+1) are both small. However, when the quantity of
recording light increases and, as a result, the recording marks
grow wider, the amplitude V(n) increases, followed by increases of
the amplitude V(n+1). The large amplitude V(n) signifies the fact
that the recording marks in the track Tr(n) are sufficiently wide.
The relatively large amplitude V(n+1) signifies the fact that the
recording marks in the track Tr(n) have grown too wide and come to
produce large spillover effects on the adjacent track Tr(n+1).
[0086] A suitable quantity of recording light can be found based on
an optimum quantity of recording light which meets both conditions
that the amplitude V(n) should be relatively large and that the
amplitude V(n+1) should be relatively small. The first condition is
met when the amplitude V(n) is, for example, in the vicinity of its
maximum value, within predetermined percentage points below the
maximum value, equal to a predetermined value, or larger than a
predetermined value. The second condition is met when the amplitude
V(n+1) is, for example, in the vicinity of 0, not larger than a
predetermined percentage points of the maximum value, equal to a
predetermined value, or smaller than a predetermined value.
[0087] If the first and second conditions are met when the quantity
of recording light is in a particular range, the optimum quantity
of recording light is desirably set to the midpoint value (or
median) of the range (a set of values) so that the designated
quantities are affected by a variety of errors to a least
extent.
[0088] Thus, the quantity of recording light is maintained at its
optimum value according to the present embodiment. Besides, in
magnetic-field-modulated recording, the quantity of recording light
is variable, but the length (size along the track) of the recording
mark remains constant; therefore, only the width of the recording
marks can be optimized through detection of changes in read-out
signals.
[0089] FIG. 3 is a flow chart showing specific steps to found an
optimum recording condition according to the method shown in FIG.
1(a) to FIG. 1(d). The process will be explained in specific detail
based on the flow chart.
[0090] An erasing pattern (a first test pattern) is recorded in the
adjacent tracks Tr(n-1) and Tr(n+1) using a large quantity of
recording light which is, for example, within a predetermined range
(Step 1). The quantity of recording light is then set to an initial
value, which is relatively low (Step 2). In Step 3, a test pattern
(a second test pattern) is recorded in the tracks Tr(n) and Tr(n+2)
using the quantity of recording light set in Step 2. The quantity
of light is then set to a predetermined reproduction value (Step
4). The test pattern is thus read from the track Tr(n) to detect
the amplitude of a read-out signal (a second read-out signal) 5
(Step 5). The detected amplitude of the signal is stored in
association with the quantity of recording light (Step 6).
Subsequently, the test pattern is read from-the track Tr(n+1) to
detect the amplitude of a read-out signal (a first read-out signal)
6 (Step 7). The detected amplitude of the signal is stored in
association with the quantity of recording light (Step 8). In Step
9, the quantity of recording light is raised by a predetermined
value. The resultant quantity of recording light is evaluated to
see if it is in a test range (Step 10). If the result of the
evaluation in Step 10 is such that the quantity of recording light
falls within a test range, the process returns to Step 3 in which
another test pattern will be recorded. If the result of the
evaluation in Step 10 is such that the quantity of recording light
falls out of a test range, the process proceeds to Step 11 in which
the amplitudes of signals stored in Step 6 and Step 8 are searched
for a range of quantities of recording light that meet the
foregoing first and second conditions. Finally, the midpoint value
of the range is designated as an optimum quantity of recording
light (Step 12).
[0091] As detailed in the description so far, according to the
present embodiment, to determine an optimum recording condition for
the track Tr(n), a condition under which a sufficiently strong
read-out signal is reproduced from the track Tr(n) is found through
detection of the amplitude V(n) of the read-out signal, and a
condition, under which recording bits do not spill over from the
track Tr(n) is found through detection of the amplitude V(n+1) of a
signal reproduced from the track Tr(n+1) which is adjacent to the
track Tr(n). Hence, an optimum recording condition can be found
precisely even when recording sensitivity differs between the
tracks Tr(n) and Tr(n+1) as is the case when information is
recorded in both the land and the groove.
[0092] The method to optimize (or to control, in general) the
quantity of recording light in accordance with the present
embodiment is not limited to the above description and may vary in
various ways. For example, subsequently to Step 1, test patterns
may be recorded in different parts of each of the tracks Tr(n) and
Tr(n+2) using recording light with a plurality of quantities,
followed by reading all the test patterns recorded in the tracks
Tr(n) and Tr(n+1) to determine an optimum recording condition.
Further, those steps which involve the detection of the amplitude
of a signal reproduced from a track and the subsequent associating
of the amplitude with the quantity of recording light may be of
course effected first on either one of the tracks Tr(n) and
Tr(n+1).
[0093] In the present embodiment, test patterns (including erasing
patterns) are written in the tracks Tr(n-1) and Tr(n+2). This is
beneficial to increase the amplitudes V(n) and V(n+1), but not
essential.
[0094] So far, the description has been focused on the optimization
(or setting, in general) of the quantity of recording light. To
optimize the strength of a recording magnetic field, the strength
of a recording magnetic field is increased gradually with the
quantity of recording light being fixed, and the aforementioned
steps are performed on the strength of a recording magnetic field.
The width of the recording marks can be controlled to be optimum
through observation of the amplitude of a reproduction signal.
Embodiment 2
[0095] Now the following description will discuss another
embodiment of the present invention in reference to FIG. 4 and FIG.
5. Here, for convenience, the members of the present embodiment
that are identical to those of embodiment 1 will not be explained
in detail, or their description will be totally omitted.
[0096] According to embodiment 1, changes were detected in the
amplitudes of signals reproduced from the track Tr(n) and its
adjacent track Tr(n+1) to determine an optimum quantity of light.
In some cases, however, this method fails and it becomes impossible
to determine an optimum quantity of light.
[0097] FIG. 4 is drawn by plotting the amplitudes V(n) and V(n+1)
of the read-out signals reproduced respectively from the track
Tr(n) and its adjacent track Tr(n+1) against the quantities of
recording light, with recording marks being written in the tracks
Tr(n) and Tr(n+2) under a recording condition illustrated in FIG.
1(b) (condition (b)), that illustrated in FIG. 1(c) (condition
(c)), and that illustrated in FIG. 1(d) (condition (d)). When the
quantity of recording light projected to the track Tr(n) increases
and, as a result, the recording marks grow wider, the amplitude
V(n) increases first. Then, the amplitude V(n+1) of a signal
reproduced from the adjacent track Tr(n+1) also increases somewhat
later but steadily due to spillover effects from the recording
marks.
[0098] In embodiment 1, conditions such that the amplitude V(n+1)
of a signal reproduced from the adjacent track Tr(n+1) equals a
predetermined threshold amplitude A0 may be designated as the upper
limit of the optimum quantity of recording light at which recording
is negatively affected by spillover effects of the recording marks.
However, in some cases, for example, when the quantity of a
recording laser beam has a limited maximum value, or when the
optical recording medium possesses irregular recording sensitivity,
a maximum quantity of recording light is still insufficient to
increase the amplitude of a signal reproduced from the adjacent
track Tr(n+1) to reach a predetermined signal amplitude A0 which is
given as a threshold value to judge whether or not recording is
negatively affected by spillover effects of the recording marks.
Embodiment 1 entails this problem.
[0099] In view of this problem, the present embodiment is adapted
to be compatible to such a case, whereby the optimum quantity of
light is determined based only on changes in the amplitude V(n) of
a signal reproduced from the track Tr(n). Explanation in detail
will be given immediately below.
[0100] Reference is now made to FIG. 4. Recording marks are written
in the track Tr(n) with a sufficient width using recording light
having a quantity at which the amplitude is sufficiently large.
However, if recording marks are written using recording light
having a quantity at which the amplitude V(n) takes its maximum
value, the resultant recording marks may be wider than the track
Tr(n) and produce spillover effects to an adjacent track Tr(n+1).
Taking this possibility into consideration, an amplitude A1 that is
slightly smaller than the maximum value of the amplitude V(n) is
designated as a threshold value, and a quantity of recording light
Px at which the amplitude V(n) is equal to the amplitude A1 is
detected as the lower limit of an optimum quantity of recording
light for the track Tr(n). An optimum quantity of recording light
Pz for the track Tr(n) is determined by so summing the quantity of
recording light Px and a predetermined quantity of recording light
Py (Pz=Px+Py) that resultant recording marks will not produce
spillover effects to adjacent tracks. It is desirable to set the
predetermined quantity of recording light Py so that it allows for
various adverse effects of errors to a greatest extent
possible.
[0101] An alternative to this scheme whereby an optimum quantity of
recording light is determined by adding a predetermined value Py to
Px is to multiplying Px by a predetermined multiplier. Other
predetermined calculations are also applicable.
[0102] FIG. 5 is a flow chart showing steps in accordance with the
method to determine recording conditions, which will be detailed in
following paragraphs. Note that description about Step 1 to Step 10
is omitted because they are identical to Step 1 to Step 10 of
embodiment 1 showing in the flow chart of FIG. 3.
[0103] Following Step 10 of embodiment 1, the amplitude associated
with the largest value among the quantities of recording light
which were stored in Step 8 and then evaluated to be within a test
range is further evaluated to see if it exceeds a predetermined
amplitude A0 (Step 20). If the result of the evaluation in Step 20
is such that the amplitude does not exceed a predetermined
amplitude A0, the quantities of recording light stored in
association with their amplitudes of signals in Step 35 are
searched for a quantity of recording light that gives the amplitude
A3 (Step 21). A predetermined quantity of recording light is added
to the quantity of recording light found in the search in Step 21
to determine an optimum quantity of recording light (Step 22). If
the result of the evaluation in Step 20 is such that the amplitude
exceeds the predetermined amplitude A0, the process proceeds to
Step 23 in which the amplitudes of signals stored in Step 6 and
Step 8 are searched, similarly to Step 11 shown in FIG. 11, for a
range of quantities of recording light that meet the predetermined
conditions. Then, the midpoint value of the range is designated as
an optimum quantity of recording light (Step 24).
[0104] As detailed in the description above, a maximum recording
condition can be determined even if the quantity of a recording
laser beam has a limited maximum value, or if the optical recording
medium possesses irregular recording sensitivity, by the method to
determine recording conditions in accordance with the present
embodiment.
[0105] In the present embodiment, an optimum quantity of recording
light has been determined based only on the amplitude V(n) of a
signal reproduced from the track Tr(n) when the upper limit of
quantities of recording light cannot be determined based on the
amplitude V(n+1) of a signal reproduced from the adjacent track
Tr(n+1). Alternatively, without any precondition, an optimum
quantity of recording light may be determined by performing a
predetermined calculation on the quantity of recording light at
which the amplitude V(n) of a signal reproduced from the track
Tr(n) equals a predetermined value.
[0106] Put it differently, this-alternative scheme can be
implemented by omitting the fourth step and substituting new steps
for the sixth step in the process of determining an optimum
quantity of recording light detailed in the description of
embodiment 1. The fourth step was a step in which the amplitude
V(n+1) of a signal 6 reproduced from the adjacent track Tr(n+1) is
detected. The new steps replacing the sixth step are those in which
a quantity of recording light is determined at which the amplitude
V(n) of a signal 5 reproduced from the track Tr(n) on which the
optimization is to be effected equals a predetermined value (the
second recording condition), a predetermined calculation is
performed on the resultant quantity of recording light, and a
recording condition under which the quantity of recording light
causes wider recording marks than does the result of the
calculation is designated as an optimum recording condition.
[0107] The alternative scheme takes less time to determine a
recording condition.
[0108] For the sake of cutting down on the time taken to determined
a recording condition, an optimum quantity of recording light can
be determined also by performing a predetermined calculation
(substraction of a predetermined value, multiplication by a
predetermined multiplier, etc.) on the quantity of recording light
at which the amplitude V(n+1) of a signal reproduced from the track
Tr(n+1) equals a predetermined value.
[0109] Specifically, this scheme can be implemented by omitting the
third step and substituting new steps for the sixth step in the
process of determining an optimum quantity of recording light
detailed in the description of embodiment 1. The third step was a
step in which the amplitude V(n) of a signal 5 reproduced from the
adjacent track Tr(n) on which the optimization is to be effected is
detected. The new steps replacing the sixth step are those in which
a quantity of recording light is determined at which the amplitude
V(n+1) of a signal 6 reproduced from the track Tr(n+1) equals a
predetermined value (the first recording condition), a
predetermined calculation is performed on the resultant quantity of
recording light, and a recording condition under which the quantity
of recording light causes smaller recording marks than does the
result of the calculation is designated as an optimum recording
condition.
[0110] To optimize the strength of a recording magnetic field, the
strength of a recording magnetic field is increased gradually with
the quantity of recording light being fixed, and the aforementioned
steps are performed on the strength of a recording magnetic field.
The width of the recording marks can be controlled to be optimum
through observation of the amplitude of a reproduction signal.
Embodiment 3
[0111] The following description will discuss another embodiment of
the present invention in reference to FIGS. 2, 6(a) to 6(d), 7, 8,
9, 10(a) to 10(c), 11, 12, and 13. Here, for convenience, the
members of the present embodiment that are identical to those of
the previous embodiments will not be explained in detail, or their
description will be totally omitted.
[0112] Those methods detailed in embodiments 1 and 2 were such that
the width of recording marks was readily controllable based on
variations in the amplitude of a signal reproduced from a specified
track and those of a signal reproduced from an adjacent track which
is affected by spillover effects. However, the detecting
sensitivity is not sufficiently high, because the amplitude V(n+1)
of a signal reproduced from the track Tr(n+1) is small as shown in
FIG. 2.
[0113] Accordingly, in the present embodiment, a method will be
discussed whereby the amplitude varies greatly so that the optimum
quantity of recording light is detectable with high
sensitivity.
[0114] Large (Wide) recording marks 21 are written (with a width
exceeding that of the track) in advance in both adjacent tracks
Tr(n-1) and Tr(n+1), using a relatively high quantity of a
recording light beam 20 as shown in FIG. 6(a). Under these
circumstances, the recording marks 21 are written based on a
recording clock according to an external clock scheme, which will
be discussed later in detail. The recording marks 21 constitute a
recording pattern which is the reverse of the pattern constituted
in the tracks Tr(n) and Tr(n+2). Hereinafter, the pattern formed in
the tracks Tr(n-1) and Tr(n+1) will be referred to as a reverse
pattern (a first test pattern), and the pattern formed in the
tracks Tr(n) and Tr(n+2) will be referred to a normal pattern (a
second test pattern).
[0115] Subsequently, recording marks 23 are written forming a
normal pattern shown in FIG. 6(b) by projecting a low quantity of a
recording light beam 22 to the track Tr(n) while reversing the
recording magnetic field. Under these circumstances, a normal
pattern is formed based on a recording clock according to an
external clock scheme, which will be discussed later in detail;
therefore, the recording marks 23 are written in phase with the
reverse pattern in an adjacent track. If the recording marks 21 in
the adjacent tracks are excessively wide, their edges will be cut
off when the recording marks 23 are written. Since the recording
marks 23 have a small width, the amplitude V10 of a signal 24
reproduced from the track Tr(n) is not sufficiently large. Besides,
the recording marks 21 are written forming a reverse pattern in the
adjacent tracks; cross-talk which occurs during reproduction
eliminates parts of the signals of the recording marks 23, further
reducing the amplitude V10. In contrast, the recording marks 21
have a large width, the amplitude V11 of a signal 25 reproduced
from the track Tr(n+1) is sufficiently large.
[0116] If the quantity of recording light is increased in an
incremental manner in the above process, the resultant recording
marks 23 grow wider in an accordingly incremental value. In FIG.
6(c) , recording marks 27 are written in the tracks Tr(n) and
Tr(n+2) using a higher quantity of a recording light beam 26 than
that of the light beam 22. A signal 28 with an amplitude V12 is
reproduced from the track Tr(n), and a signal 29 with an amplitude
V13 is reproduced from the adjacent track Tr(n+1).
[0117] As the quantity of recording light is increased, the
recording marks 21 have their edges being cut off and grow narrower
accordingly. In addition, the recording marks in the adjacent
tracks grow wider, causing more cross-talk. In FIG. 6(d) ,
recording marks 31 are written with a greater width than the tracks
Tr(n) and Tr(n+2) by writing a normal pattern while projecting a
larger quantity of recording light beam 30 than that of the light
beam 26 on the tracks Tr(n) and Tr(n+2). The read-out signal 32 has
a sufficiently large amplitude V14. Under these circumstances, the
recording marks 21 have their edges being cut off during the
process of the magnetic-field-modulated recording. This leaves the
middle parts intact, which will become recording marks 34. Since
the recording marks 34 has a smaller width, the amplitude V15 of
the reproduction signal 33 is not sufficiently large. Besides,
cross-talk from the recording marks 31 in the adjacent tracks
eliminates parts of signals of the recording marks 34, further
reducing the amplitude. These facts signify that the amplitude of a
reproduction signal is reduced by cross-erase as a result of an
increased quantity of recording light and further reduced by
cross-talk from the reverse pattern in the adjacent tracks.
[0118] FIG. 7 shows the amplitudes V(n) and V(n+1) of reproduction
signals showing in FIG. 6 (b), FIG. 6 (c), and FIG. 6(d). It is
understood from FIG. 7 that a1 is far smaller than a2, where al is
the amplitude V(n) when the quantity of recording light is low, and
a2 is the amplitude V(n) in embodiments 1 and 2. This is because
parts of recording marks forming the normal pattern are eliminated
by cross-talk from the reverse pattern in the adjacent tracks.
Under these circumstances, the amplitude V(n+1) of a signal
reproduced from the reverse pattern in the adjacent track is large.
When the quantity of recording light is increased, the recording
marks grow wider, and the cross-talk decrease. As a result, the
amplitude V(n) increases gradually. When the quantity of recording
light is further increased, the recording marks forming a reverse
pattern have their edges cut off gradually, and the amplitude
V(n+1) decreases significantly.
[0119] When the quantity of recording light is such that both the
amplitudes V(n) and V(n+1) are large, the recording marks are wide
in the track Tr(n), and there occurs little cross-talk in the
adjacent tracks. For these reasons, the quantity of recording light
that satisfies these conditions should be designated as an optimum
quantity of recording light. Specifically, two conditions should be
met: the first one is such that when the amplitude V(n) is, for
example, in the vicinity of its maximum value, within predetermined
percentage points below the maximum value, equal to a predetermined
value, or larger than a predetermined value, and the second
condition is such that the amplitude V(n+1) is, for example, in the
vicinity of its maximum value, within predetermined percentage
points below the maximum value, equal to a predetermined value, or
larger than a predetermined value. The optimum quantity of
recording light is desirably set to the midpoint value of the range
of the quantity of recording light satisfying the two conditions,
since the setting leaves sufficient margins.
[0120] Writing reverse patterns in adjacent tracks in this manner,
the amplitude varies greatly in comparison to embodiments 1 and 2,
so that the optimum quantity of recording light is detectable with
high sensitivity.
[0121] In some cases, for example, when the quantity of a recording
laser beam has a limited maximum value, or when the optical
recording medium possesses irregular recording sensitivity, a
maximum quantity of recording light is still insufficient to
increase the amplitude of a signal reproduced from the adjacent
track Tr(n+1) to reach a predetermined signal amplitude A2 which is
given as a threshold value to judge whether or not recording is
negatively affected by spillover effects of the recording marks as
shown in FIG. 8. In such an event, an optimum quantity of recording
light is determined based only on the amplitude V(n) of a signal
reproduced from the track Tr(n).
[0122] If recording marks are written using recording light having
a quantity at which the amplitude V(n) takes its maximum value, the
resultant recording marks may be wider than the track Tr(n). Taking
this possibility into consideration, a quantity of recording light
Px is detected which gives an amplitude A3 that is slightly smaller
than the maximum amplitude as shown in FIG. 8. An optimum quantity
of recording light Pz for the track Tr(n) is determined by so
summing the quantity of recording light Px and a predetermined
quantity of recording light Py that resultant recording marks will
not produce spillover effects to adjacent tracks (alternatively, by
performing a predetermined calculation on Px, e.g., multiplication
of Px by a predetermined multiplier).
[0123] In the above description, an optimum quantity of recording
light has been determined based only on the amplitude V(n) when the
amplitude V(n+1) does not decrease to a predetermined value A2.
Alternatively, without any precondition, an optimum quantity of
recording light may be determined based only on the amplitude
V(n).
[0124] In the present embodiment described so far, test patterns
(including erasing patterns) have been written in the tracks
Tr(n-1) and Tr(n+2). This is beneficial to increase the amplitudes
V(n) and V(n+1), but not essential.
[0125] Now, referring to FIG. 9, an optical recording device will
be explained which executes a method of controlling recording
conditions in the same manner as that shown in FIG. 6(a) to FIG.
6(d). An identical optical recording device can be used to execute
the method of controlling recording conditions in accordance with
embodiment 1.
[0126] During the formation of a test pattern, the CPU (optimum
recording condition determining means) 46 sends a control command
c3 to a recording light quantity determining circuit 50 which
produces a recording light quantity control signal p2 as an output.
The recording light quantity control signal p2 is transmitted to a
drive circuit 47 via a switching circuit 48 according to a
switching command c2 from the CPU 46. Receiving a drive current f
from the drive circuit 47, the semiconductor laser 41 projects a
strong laser beam b1 to a magneto-optical disk 40. Simultaneously,
the CPU 46 sends a control command c4 to a test pattern generating
circuit 53 which produces a recording signal g in normal and
reverse patterns shown in FIG. 4. As the recording signal is
received by the drive circuit 52, the magnetic head 51 generates,
from a drive current h, a recording magnetic field which writes
normal and reverse patterns on the magneto-optical disk 40. In this
device, the CPU 46, the recording light quantity determining
circuit 50, the test pattern generating circuit 53, the drive
circuits 47 and 52, the semiconductor laser 41, and the magnetic
head 51 constitute recording means.
[0127] Now, the detection of the amplitude of a reproduction signal
will be discussed. Responsive to the switching command c2 sent from
the CPU 46, a reproduction light quantity determining circuit 49
sends a reproduction light quantity control signal P1 to the drive
circuit 47 via the switching circuit 48. Receiving the drive
current f, the semiconductor laser 41 projects a weak laser beam b1
to the magneto-optical disk 40. The reflection beam b2 is guided to
a photodiode 42. Read-out signals r1 and r2 are reproduced from the
magneto-optical disk 40. The former will be amplified by an
amplifier 43. The latter will be provided to an A/D converter 44
and a clock deriving circuit 45. The clock deriving circuit 45
derives an external clock c from the reproduction signal r2 and
sends it to the test pattern generating circuit 53. Thus, the
normal pattern is written in the target track in phase with the
reverse pattern in an adjacent track. The external clock c is also
transmitted to the A/D converter 44 where a read-out signal r2 is
converted to digital values d. The digital values d is transmitted
to the CPU 46 where the amplitude of the read-out signal r2 is
detected. In this device, the CPU 46, the photodiode 42, the
amplifier 43, and the A/D converter 44 constitute read-out
means.
[0128] The photodiode 42, the semiconductor laser 41, and the
magnetic head 51 are disposed in a pickup 55 which is denoted by
dotted lines in FIG. 9. Responsive to a control command cl from the
CPU 46, a pickup drive device 54 drives the pickup 55 in such a
manner that the pickup 55 can move and project the light beam b1
onto the target tracks Tr(n) and Tr(n+2) and the non-target tracks
Tr(n-1) and Tr(n+1) shown in FIG. 6(a) to FIG. 6(d).
[0129] The CPU 46 sends a control command c3 to cause the quantity
of recording light to gradually increase, a control command c1 to
cause the light beam to move to a predetermined track, and a
control command c4 to causes a normal pattern to be written. The
CPU 46 sets the light beam b1 to the quantity of reproduction light
through a control command c2 and detects the amplitude of the
read-out signal r2 based on the input digital values d. Then, the
CPU 46 sequentially stores an amplitude for every quantity of
recording light and designates a quantity of recording light that
satisfies predetermined conditions as an optimum quantity of
recording light.
[0130] FIG. 10(a) illustrates in detail the clock deriving circuit
45 shown in FIG. 9. A two-part photodetector 42a receives the
reflection beam b2 from the magneto-optical disk 40. Two output
signals r2a and r2b are supplied to a differential amplifier 45a in
the clock deriving circuit 45 to produce a well-known push-pull
tracking error signal j. The tracking error signal j carries in it
a read-out signal (will be explained later in detail) from a
reference mark 58. To detect the reference mark 58, a hysteresis
comparator 45b compares the tracking error signal j with ground
level to produce a reference mark detection signal k. When the
hysteresis comparator 45b supplies the reference mark detection
signal k to a PLL circuit 45c, the PLL circuit 45c produces an
external clock c for output in phase with the reference marks
58.
[0131] FIG. 10(b) and FIG. 10(c) are waveform diagrams illustrating
operations of the clock deriving circuit 45 of FIG. 10(a). In FIG.
10(b), the normal and reverse patterns are written in the
respective tracks, i.e., the land 59 and the groove 60. Here, for
convenience, we will designate the groove 60 as the track Tr(n) and
the land 59 as the track Tr(n-1), and no description will be given
to the tracks Tr(n+1) and Tr(n+2). Reference marks 58 and test
pattern recording areas 57 are arranged alternately along the
tracks. Recording marks 56 are written in the test pattern
recording area 57, forming a normal or reverse pattern. The
sidewall 62 between the land 59 and the groove 60 wobbles with a
certain period so as to record the non-erasable reference marks 58
which provide a physical reference regarding the positioning of the
magneto-optical disk. Only the sidewall 62 between the land 59 and
the groove 60 wobbles, and the opposite sidewalls 63 and 64 do not
wobble. This arrangement restrains cross-talk from reference marks
(not shown) which are adjacent to the reference marks 58 of
interest in the direction perpendicular to the tracks. A test
pattern recording area 57 is provided in every area between two
adjacent reference marks 58.
[0132] For example, if a light spot 61 is used to perform tracking
on the groove 60, the tracking error signal j carries over it a
signal reproduced from a reference mark 58 as shown in FIG. 10(c).
By binarizing the signal, the reference mark detection signal k is
obtained. The reference mark detection signal k is provided to the
PLL circuit 45c to obtain an external clock c which is in phase
with the reference mark 58.
[0133] The device detailed here may be applicable to all the
methods to determining recording conditions in accordance with
embodiments of the present invention. Further, the device, although
having been described so far in connection with an external clock,
may adopt a clock produced by different means and is still capable
of perform its tasks.
[0134] Now, referring to the flow chart of FIG. 11, a method to
determine recording conditions will be explained in detail in
accordance with the present embodiment.
[0135] A reverse pattern is written in advance in the adjacent
tracks Tr(n-1) and Tr(n+1), using a large quantity of recording
light (Step 30). The quantity of recording light is set to an
initial value which is relatively low (Step 31). A normal pattern
is written in the tracks Tr(n) and Tr(n+2), using recording light
with a quantity equal to the value set in Step 31 (Step 32). The
light quantity of reproduction light is then set to a predetermined
value (Step 33). The normal pattern in the track Tr(n) is read to
detect the amplitude of a reproduction signal (Step 34). The
amplitude is stored in association with the quantity of recording
light (Step 35). Then, the reverse pattern in the track Tr(n+1) is
read to detect the amplitude of a reproduction signal (Step 36).
The amplitude is stored in association with the quantity of
recording light (Step 37). The quantity of recording light is
increased by a predetermined value (Step 38). The increased
quantity of recording light is evaluated to see if it exceeds a
test range (Step 39).
[0136] If the result of the evaluation in Step 39 is such that the
quantity of recording light does not exceed a test range, the
process returns to Step 32 in which another normal pattern is
written. In contrast, if the result of the evaluation in Step 39 is
such that the quantity of recording light exceeds a test range, the
amplitude associated with the largest value among the quantities of
recording light which were stored in Step 37 and then evaluated to
be within a test range is further evaluated to see if it is smaller
than a predetermined amplitude A2 (Step 40).
[0137] If the result of the evaluation in Step 40 is such that the
amplitude is equal to, or larger than, the predetermined amplitude
A2, the quantities of recording light stored in association with
their amplitudes of signals in Step 35 are searched for a quantity
of recording light that gives the amplitude A3 (Step 41). A
predetermined quantity of recording light is added to the quantity
of recording light found in the search in Step 41 to determine an
optimum quantity of recording light (Step 42). If the result of the
evaluation in Step 40 is such that the amplitude is smaller than
the predetermined amplitude A2, the process proceeds to Step 43 in
which the quantities of recording light stored in association with
amplitudes in Step 35 and Step 36 are searched for a range of
quantities of recording light that meet a predetermined condition.
Finally, the midpoint value of the range is designated as an
optimum quantity of recording light (Step 44).
[0138] Now, data obtained from measurement of changes in the
amplitude of a reproduction signal will be explained by way of an
example of two different lengths of marks and empty spaces which
are used to form the normal and reverse patterns. Reference is made
to FIG. 12 and FIG. 13.
[0139] FIG. 12 shows the amplitudes of reproduction signals when
the quantities of recording light disclosed in Japanese Laid-Open
Patent Application No. 11-73700/1999 are used and those when the
quantities of recording light obtained according to the method of
controlling the strength of a recording magnetic field are used.
According to the method, a reverse pattern is written first in both
of the adjacent tracks of a specified track with a relatively high
quantity of recording light, before a normal pattern is written in
the specified track with a predetermined quantity of recording
light. Then, a reverse pattern is again written in the adjacent
tracks with the same quantity of recording light as a normal
pattern was written in the specified track. Finally, the specified
track is read. Throughout these operations, the laser beam has a
wavelength of 635 nm, the objective lens has an aperture ratio of
0.6, and the channel bit has a length T (modulated bit unit used in
recording) of 47 ns. It is understood that when the mark length and
the empty space length are both equal to 2 T or 4 T, changes are
detectable in the amplitude of a signal resulting from the use of a
quantity of recording light. Put it differently, changes in the
amplitude of a signal are detectable if the mark length and the
empty space length are both 2 T or greater.
[0140] Even under different conditions, for example, when the laser
beam changes in its wavelength or the objective lens changes in its
aperture ratio, the value 2 T of the mark length and the empty
space length is still valid in detecting changes in the amplitude
of a signal. That is, even under the different conditions, the mark
length and the empty space length are both equal to 2 T.
[0141] Displacements of recording marks were measured which
occurred along the track due to a difference in the quantity of
recording light. They were measured using a laser beam of the same
wavelength, an objective lens of the same aperture ratio, and the
channel bit of the same length as stipulated in FIG. 12. Results
are shown in FIG. 13, which indicates that when the quantity of
recording light is increased, temperature rises in an increasingly
large portion of the optical recording medium, and therefore the
recording mark is displaced opposite to the movement of the light
spot.
[0142] Therefore, if data is collected in advance on displacements
of recording marks which occur along the track due to different
quantities of recording light as shown in FIG. 13, and there is
provided means to correct a displacement of a recording bit
according to the quantity of recording light (displacement
correction means), marks and empty spaces can be arranged so that
marks are aligned to marks or empty spaces along the direction
perpendicular to the tracks in the reverse and normal patterns. If
the mark length and the empty space length are both greater than 2
T, an optimum quantity of recording light is detectable based on a
change in the amplitude of a signal. The displacement correction
means may be, for example, the means disposed in between the clock
deriving circuit 45 and the test pattern generating circuit 53
along the path of the external clock c (see FIG. 9) so as to change
the phase of the external clock c according to the quantity of
recording light. As to a third test pattern used in embodiment 5
(will be discussed later in detail), marks and empty spaces that
form a reverse pattern in the tracks Tr(n), Tr(n+1), etc. can be
arranged so that marks are aligned to marks or empty spaces along
the direction perpendicular to the tracks if displacement
correction means is provided similarly.
[0143] If the mark length and the empty space length are equal to,
or greater than, the length of a channel bit that is required to
prevent the displacement of a recording bit from producing adverse
effects within a test range for the quantity of recording light,
the length of a recording mark is great when measured along the
track. Therefore, around the midpoint of the recording mark, the
record position is not displaced due to the variable quantity of
recording light. By detecting the amplitude of a signal on which
sampling is carried out around the midpoint of a recording mark, an
optimum quantity of recording light becomes detectable without
providing the means that corrects the displacement of a recording
bit according to the quantity of recording light.
[0144] Suppose in FIG. 13 that the track Tr(n) is a groove, the
test range for the quantity of recording light is from 8 mW to 13
mW, and the relatively high quantity of recording light which was
used at the beginning (in the first step) in the recording in both
of the adjacent tracks Tr(n-1) and Tr(n+1) was 11 mW. In this
environment, the recording positions are located at about 40 ns in
the adjacent tracks Tr(n-1) and Tr(n+1) in the first step, and the
recording positions are located at about 130 ns in the tracks Tr(n)
and Tr(n+2) in the third step with a quantity of recording light of
8 mW. Thus, the displacement of the recording bit amounts to about
90 ns. Therefore, the channel bit needs to have a length of 2 T to
prevent the displacement of the recording bit from producing
adverse effects. Besides, if the quantity of recording light equals
13 mW, the recording positions are located at about 30 ns in the
tracks Tr(n) and Tr(n+2). Thus, the displacement of the recording
bit occurs in the opposite direction to the previous case,
amounting to about 10 ns. Therefore, the channel bit needs to have
a length of 1 T to prevent the displacement of the recording bit
from producing adverse effects.
[0145] Overall, the channel bit needs to have a length of 3 T to
prevent the displacement of the recording bit from producing
adverse effects.
[0146] Further, since the channel bit needs to have a length of 2 T
to detect the amplitude of a signal as mentioned in the above, the
mark length and the empty space length are preferably equal to, or
greater than, 2 T +3 T=5 T provided that the track Tr(n) is a
groove and also that the magneto-optical recording medium possesses
characteristics shown in FIG. 13.
[0147] The description so far was based on an assumption that the
track Tr(n) was a groove. When the track Tr(n) is a land, the empty
space length can be determined in a similar manner so that the
displacement can be successfully prevented from producing adverse
effects.
[0148] If identical mark length and empty space length are to be
used to determine the quantity of recording light for the groove
and the land, the mark length and the empty space length are
preferably determined so as to encompass the largest displacement
in the same direction as the movement of a light spot and also in
the opposite direction. Suppose that the magneto-optical recording
medium possesses characteristics shown in FIG. 13, the test range
for the quantity of recording light is from 8 mW to 13 mW, and the
relatively high quantity of recording light which was used at the
beginning (in the first step) in the recording in both of the
adjacent tracks Tr(n-1) and Tr(n+1) was 11 mW. In this environment,
if the adjacent track Tr(n+1) is a land, a displacement of the
recording bit occurs during recording in the groove (track Tr(n))
with a quantity of recording light of 8 mW, amounting to about 90
ns. Therefore, the channel bit needs to have a length of 2 T to
prevent the displacement of a recording bit from producing adverse
effects. If the adjacent track Tr(n+1) is a groove, a displacement
of a recording bit occurs during recording in the land (track
Tr(n)) with a quantity of recording light of 13 mW, amounting to
about 55 ns. Therefore, the channel bit needs to have a length of 2
T to prevent the displacement of a recording bit from producing
adverse effects. Therefore, the channel bit needs to have a length
of 4 T (=2 T+2 T) to prevent the displacement of a recording bit
from producing adverse effects. Therefore, the mark length and the
empty space length are both preferably equal to, or greater than, 2
T+4 T=6 T.
[0149] As detailed so far, provided that the two different lengths
of marks and empty spaces which are used to form the normal and
reverse patterns are both equal to, or greater than,
(2+L).multidot.T, where L.multidot.T is the length of a channel bit
that is required to prevent the displacement of a recording bit
from producing adverse effects under a certain recording condition,
an optimum quantity of recording light becomes detectable without
providing any means that corrects the displacement of a recording
bit according to the quantity of recording light.
[0150] An optimum value is also available with high sensitivity
when the marks and the empty spaces are of different lengths.
However, if they share the same length, the direct current
component of a signal can be rendered as being 0, and the amplitude
of a signal can be detected with high precision in the detection of
the amplitude (alternating current component) of the signal.
Embodiment 4
[0151] Another embodiment of the present invention will be
discussed in reference to FIG. 14(a) to FIG. 14(c), FIG. 15, and
FIG. 16. However, for convenience, the members of the present
embodiment that are identical to those of the previous embodiments
will not be explained in detail, or their description will be
totally omitted.
[0152] In embodiment 3, we discussed a method and device to detect
a change in the amplitude of a signal with high sensitivity by
writing a reverse pattern in adjacent tracks. In the present
embodiment, we will discuss a method to detect a change in the
amplitude of a signal with further enhanced sensitivity.
[0153] Large (Wide) recording marks 71 are written in advance in
tracks Tr(n) and Tr(n+2), using a high quantity of a light beam 70
as shown in FIG. 14(a). The quantity of recording light here only
needs to be moderately high, because the only requirement is such
that some parts remain unerased (will be explained later in
detail). Preferably, the quantity of recording light is higher than
a typical value to write wide recording marks as mentioned above.
The recording marks 71 constitute a recording pattern which is
identical to the aforementioned reverse pattern (the third test
pattern).
[0154] Subsequent operations illustrated in FIG. 14(b) and FIG.
14(c) are identical to those in embodiment 3. That is, wide
recording marks 21 are written (with a width exceeding that of the
track) in both adjacent tracks Tr(n-1) and Tr(n+1), using a
relatively high light quantity of a recording light beam 20 as
shown in FIG. 14(b). The recording marks 21 constitute a recording
pattern which is a reverse pattern. Thus, the wide recording marks
71 written in advance in the tracks Tr(n) and Tr(n+2) have their
edges cut off, leaving narrower recording marks 72.
[0155] Recording marks 23 are then written constituting a normal
pattern as shown in FIG. 14(c) by projecting a relatively low
quantity of recording light beam 22 to the tracks Tr(n) and
Tr(n+2). Here, in the track Tr(n) of interest, the normal pattern
23 is overwritten on the reverse pattern 72 as shown in FIG. 14
(b). If the quantity of recording light is low, the reverse pattern
remains unerased in many parts as shown in FIG. 14(c), which
reduces the amplitude of a signal reproduced from the normal
pattern. When the quantity of recording light is reduced, the
reverse pattern remains unerased in correspondingly more parts, and
the amplitude reproduced from the normal pattern decreases further
accordingly. The more the reverse pattern is preserved, the more
the amplitude is reduced.
[0156] Referring to FIG. 15, the reduction in the amplitude V(n) of
a signal reproduced from a normal pattern will be explained. In a
case when a reverse pattern is not written in advance in the track
Tr(n) as in embodiment 2, the amplitude V(n) increases gradually
with an increase in the quantity of recording light as denoted by a
solid line a3. In contrast, in a case when a reverse pattern is
written in advance in the track Tr(n), the amplitudes are lower at
low quantities of recording light due to the unerased parts of the
reverse pattern as denoted by a dotted line a4 in FIG. 15. This
indicates that a smaller quantity of recording light results in an
correspondingly more and larger unerased parts, and the amplitude
decreases by correspondingly larger amounts. Therefore, the method
in accordance with the present embodiment is advantageous to a case
where no reverse pattern is written in advance in the track Tr(n)
in that the amplitude changes by large amounts and an optimum value
are detectable with enhanced sensitivity.
[0157] The amplitude grows larger also if a reverse pattern is
written only in the tracks Tr(n) and Tr(n+2) (not in the adjacent
tracks Tr(n-1) and Tr(n+1)), using a relatively high quantity of
recording light.
[0158] FIG. 16 is a flow chart showing operations to control
recording conditions illustrated in FIG. 14(a) to FIG. 14(c).
First, a reverse pattern is written in advance in the tracks Tr(n)
and Tr(n+2), using a relatively high quantity of recording light
(Step 50). Subsequent operations are identical to those shown in
the flow chart of FIG. 11 (embodiment 3). An optimum quantity of
recording light is thus determined.
[0159] In the present embodiment described so far, test patterns
(including erasing patterns) have been written in the tracks
Tr(n-1) and Tr(n+2). This is beneficial to increase the amplitudes
V(n) and V(n+1), but not essential.
Embodiment 5
[0160] Another embodiment of the present invention will be
discussed in reference to FIG. 17. However, for convenience, the
members of the present embodiment that are identical to those of
the previous embodiments will not be explained in detail, or their
description will be totally omitted. The present embodiment
discloses a method whereby a maximum amplitude is obtained of a
signal reproduced from a normal pattern of the track Tr(n) and of a
signal reproduced from a reverse pattern of the adjacent track
Tr(n+1), the changes in the amplitudes are normalized using the
obtained maximum amplitudes as the reference (In the device shown
in FIG. 9, the CPU 46 performs normalization as normalize means),
and those quantities of recording light that meet a predetermined
condition are obtained based on an identical-predetermined
amplitude to determine an optimum quantity of recording light.
[0161] It is highly likely that the track Tr(n) and the adjacent
track Tr(n+1) have different reproduction sensitivity and the
amplitudes of signals reproduced from the individual tracks
mentioned in embodiment 3 and 4 have different signal levels.
[0162] If recording marks are written in the track Tr(n) with an
increasingly large quantity of recording light, the resultant
recording marks grow wider and the amplitude V(n) converges at a
moderate value. This indicates that the recording marks
constituting a normal pattern have grown wider than the light spot
used for reproduction. Meanwhile, the amplitude V(n+1) of a signal
reproduced from the adjacent track Tr(n+1) is not affected by
spillover effects of recording marks constituting a normal pattern,
because the recording marks are narrow if a relatively small
quantity of recording light is projected to the track Tr(n).
Therefore, once the amplitude reaches a moderately large value, it
no longer grows. This is also because the recording marks
constituting a reverse pattern have grown wider than the light spot
used for reproduction.
[0163] The maximum values of the amplitudes V(n) and V(n+1),
although possessing different signal levels due to a difference in
sensitivity, serve as an identical reference in the sense that
these are both amplitudes of a signal reproduced from recording
marks that are as wide as, or wider than, the light spot.
[0164] Therefore, if the changes in the amplitudes are normalized
using the respective maximum amplitudes, an optimum quantity of
recording light can be detected sharing a single predetermined
amplitude as a sole reference.
[0165] For example, the maximum amplitude value is normalized to 1
as shown in FIG. 17. A recording condition is can be selected under
which the amplitude V(n) of a signal reproduced from the track
Tr(n) is equal to, or greater than .alpha.1 (0<.alpha.1<1)
and the normalized of the amplitude V(n+1) of a signal reproduced
from the adjacent track Tr(n+1) is equal to, or greater than,
.alpha.1 (0<.alpha.1<1). To obtain a large margin for the
quantity of recording light, the midpoint quantity of recording
light in the range is desirably designated as an optimum recording
condition.
Embodiment 6
[0166] Another embodiment of the present invention will be
discussed in reference to FIG. 18. However, for convenience, the
members of the present embodiment that are identical to those of
the previous embodiments will not be explained in detail, or their
description will be totally omitted.
[0167] The methods and devices in accordance with embodiments 3 and
4 were to detect both the amplitude of a signal reproduced from a
normal pattern in the track Tr(n) and the amplitude of a signal
reproduced from the reverse pattern in the adjacent track Tr(n+1).
In the present embodiment, a method will be explained to determine
recording conditions for the track Tr(n) through the detection of
only the changes of the amplitude of a signal reproduced from the
adjacent track Tr(n+1) to speed up the process.
[0168] Spillover effects from the marks that are written in the
track Tr(n) to constitute a normal pattern can be estimated from
the changes in the amplitude of a signal reproduced from the
adjacent track Tr(n+1). Therefore, an optimum quantity of recording
light Pz for the track Tr(n) can be determined which can write
marks without producing spillover effects to the adjacent track
Tr(n+1), by detecting the quantity of recording light (for example,
the quantity of light at which the amplitude V(n+1) falls down to
or below a predetermined value A4) at which spillover effects from
the marks appear and performing a calculation on the detected
quantity of recording light. Px (substraction of a predetermined
quantity of recording light Py (=Px-Py), multiplication by a
predetermined multiplier, etc.)
[0169] According to this method, spillover effects from the pattern
written in the track Tr(n) is measured through the reading of the
adjacent track Tr(n+1), and a recording condition which produces no
such effects is designated as the recording condition for the track
Tr(n). As a result, recording conditions can be precisely obtained
for the track Tr(n) even when recording sensitivity differs between
the track Tr(n) and the track Tr(n+1).
Embodiment 7
[0170] Another embodiment of the present invention will be
discussed in reference to FIGS. 6(a) to FIG. 6(d), FIG. 19(a), and
FIG. 19(b). However, for convenience, the members of the present
embodiment that are identical to those of the previous embodiments
will not be explained in detail, or their description will be
totally omitted. In the present embodiment, a method will be
explained whereby the amplitude of a signal is detected for changes
with further enhanced sensitivity while reducing adverse effects to
the amplitude of a signal from circumferential variations of the
track.
[0171] The amplitude of a signal is not always constant even in a
single turn of the track due to various adverse effects including a
tilt and a difference in sensitivity. For example, supposing that
there is a tilt in single turn of the track as shown in FIG. 19(a),
the amplitude of a signal varies even when it is reproduced from
the marks written with an identical width in the track as shown in
FIG. 19(b). The present embodiment addresses this problem. The
following description will be based on the method to determine
recording conditions in accordance with embodiment 3 (FIGS. 6(a) to
6(d)).
[0172] Here, a wide reverse pattern 21 is formed in advance in both
the adjacent tracks Tr(n-1) and Tr(n+1) with a great light quantity
of a recording light beam 20, and the amplitude of a signal
reproduced from the adjacent track Tr(n+1) is detected and stored
in association with a circumferential position (position in the
track direction). Thereafter, a normal pattern is formed in the
track Tr(n) with a predetermined quantity of recording light,
followed by the detection of the amplitude of a signal reproduced
from the track Tr(n) and the adjacent track Tr(n+1).
[0173] By detecting the amplitude of a signal reproduced from the
adjacent track Tr(n+1) before a normal pattern is formed in the
track Tr(n) in this manner, the amplitude of a signal reproduced
form the normal pattern formed in the track Tr(n) and the adjacent
track Tr(n+1) can be normalized in association with a
circumferential position based on the amplitude (normalization to
correct the differences of circumferential positions, effected by
the CPU 46 in the case of the device shown in FIG. 9 as a single
cycle variation normalization means). The normalization is effected
every time a recording condition is changed. Thus, the adverse
effects to the amplitude of a signal are reduced which occur due to
a circumferential variation in a single cycle of the track, and
sensitivity is enhanced in detecting changes in the amplitude of a
signal.
[0174] The normalization can be effected, for example, based on a
mean value of the amplitudes of a signal reproduced from-the
adjacent track Tr(n+1) for every area in which the quantity of
recording light is specified. In other words, first, the amplitude
of a signal reproduced from the adjacent track Tr(n+1) in which a
reverse pattern 21 is written is obtained in advance in an area in
which the quantity of recording light is specified, and the means
value of the amplitudes is obtained over the area in which the
quantity of recording light is specified. The amplitudes of signals
reproduced from the track Tr(n) and the adjacent track Tr(n+1) are
normalized using the mean value after a normal pattern is written
in the track Tr(n).
[0175] The present embodiment is intended to restrain variations in
the amplitude that occur in the circumferential direction due to a
tilt and some other factors. Even if the amplitude of a signal from
the adjacent track Tr(n+1) before a normal pattern is formed in it
is used to normalize the amplitude of a signal reproduced from the
adjacent track Tr(n+1) as well as that of a signal reproduced from
the track Tr(n) as described above, the amplitude varies due to a
tilt and other factors only in the circumferential direction and
does not vary between adjacent tracks (for example, between the
land and the groove), which poses no problem.
[0176] The method in accordance with the present embodiment is
applicable to embodiment 4 with slight modifications. The amplitude
of a signal reproduced from a reverse pattern (the third test
pattern) formed in the track Tr(n) may be used to normalize the
amplitudes of signals reproduced from the normal patterns formed in
the track Tr(n) and the adjacent track Tr(n+1) under predetermined
recording conditions. Alternatively, the amplitude of a signal
reproduced from a reverse pattern (the third test pattern) formed
in the track Tr(n) may be used to normalize the amplitude of a
signal reproduced from the normal pattern formed in the track
Tr(n), and then the amplitude of a signal reproduced from a reverse
pattern formed in the adjacent track Tr(n+1) may be used to
normalize the amplitude of a signal reproduced from the normal
patterns formed in the adjacent track Tr(n+1).
[0177] The method in accordance with the present embodiment is
applicable also to embodiment 5. In the event, two kinds of
normalization are effected to restrain variations of the amplitude
in the circumferential direction in accordance with the present
embodiment and to correct differences in sensitivity between
adjacent tracks.
[0178] The description so far has described some embodiments of the
present invention; however, the present invention is not limited to
such embodiments only and for example is applicable in optimization
of the strength of a recording magnetic field. Further, although
magnetic field modulation recording has been cited as an example,
the present invention is also similarly applicable to optical
modulation recording, in which event the amplitude of a signal can
be used to detect changes in the width of recording marks and an
optimum quantity of recording light can be obtained with high
sensitivity.
[0179] Besides, recording conditions can be changed for every
sector to obtain an optimum quantity of recording light.
[0180] Alternatively, a plurality of sets of recording conditions
may be stipulated for a single sector to obtain an optimum quantity
of recording light.
[0181] Throughout the embodiments discussed above, the amplitude
was obtained either of the signal reproduced from the specified
track Tr(n) (the second read-out signal) or the signal reproduced
from the adjacent track Tr(n+1) (the first read-out signal), before
an optimum quantity of recording light was obtained based on the
amplitude. The present invention is not limited to amplitude
values. Those conditions under which the second read-out signal and
the first read-out signal are in a predetermined state (for
example, those conditions under which the second read-out signal
and the first read-out signal have predetermined jitters or error
rates) are obtained, before an optimum quantity of recording light
was obtained based on the amplitude.
[0182] An optimum recording condition is obtainable, for example,
by (i) writing the first and second test patterns as shown in FIGS.
6(a) to 6(d) and FIGS. 14(a) to 14(c) and designating as an optimum
recording condition a condition under which the second read-out
signal has a small jitter (or a small error rate) and the first
read-out signal has a small jitter (or a small error rate); (ii)
writing the first and second test patterns as shown in FIGS. 6(a)
to 6(d) and FIGS. 14(a) to 14(c), performing a predetermined
calculation on a recording condition under which the second
read-out signal has a desirable jitter value (for example,
somewhere between 10% to 20%) or the error rate has a desirable
value (for example, somewhere between 10.sup.-4 to 10.sup.-3), and
designating as an optimum recording condition a condition under
which larger recording marks can be formed than under those
recording conditions; (iii) writing the first and second test
patterns as shown in FIGS. 6(a) to 6(d) and FIGS. 14(a) to 14(c),
performing a predetermined calculation on a recording condition
under which the first read-out signal has a desirable jitter value
(for example, somewhere between 10% to 20%) or the error rate has a
desirable value (for example, somewhere between 10.sup.-4 to
10.sup.-3), and designating as an optimum recording condition a
condition under which larger recording marks can be formed than
under those recording conditions. When the first and second test
patterns are formed as shown in FIGS. 1(a) to 1(d) similarly, an
optimum recording condition is obtainable based on the jitter or
error rate of either the second read-out signal or the first
read-out signal, or both. Particularly, if optimum recording
conditions are obtained based on the jitters and error rates of
both the signal reproduced from the specified track (the second
read-out signal) and the signal reproduced from the adjacent track
(the first read-out signal), a sufficient reproduction signal is
obtainable as a reproduction signal from the specified track, and
optimum recording conditions which are free from cross-erase are
obtainable from the signal reproduced from the adjacent track.
Therefore, recording conditions can be obtained even when there is
difference in recording sensitivity between adjacent tracks.
[0183] Further, throughout the foregoing embodiments, an optimum
recording condition was obtained by the use of the amplitude of a
read-out signal. Therefore, normalization was effected in
embodiment 5 and in embodiment 7 in the circumferential direction,
by the use of the amplitude value of a read-out signal. The present
invention is not limited to this. Normalization can be effected by
the use of a quantity detected from a read-out signal, such as the
jitter and the error rate.
[0184] Further, although an external clock was produced from a
sidewall between a land and a groove as a reference mark throughout
the foregoing description, it can be reproduced from anything that
is prerecorded on the optical recording medium to provide a
reference mark.
[0185] Throughout the embodiments above, a push-pull signal was
used to produce an external clock. Any other signal from which a
reference mark is detectable may be used, including a tangential
push-pull signal, an RF sum signal, etc.
[0186] In embodiments 1 and 2, an erasing pattern was used as the
first test pattern. The present invention is not limited to this.
In embodiments 3 to 7, a reverse pattern was used as the first test
pattern, and a normal pattern as the second test pattern. The
present invention is not limited to this. The first and second test
patterns only need to be different from each other.
[0187] Throughout the embodiments, magneto-optical recording was
being considered. The invention, however, is similarly applicable
to other types of optical recording medium, such as one that
utilizes on phase transition.
[0188] As described in detail in the foregoing, the optical
recording method in accordance with a first invention is an optical
recording method of recording information on an optical recording
medium, including the steps of:
[0189] (a) recording a first test pattern in a first track on the
optical recording medium under such a predetermined recording
condition to form a wide recording mark;
[0190] (b) after the recording of the first test pattern, recording
a second test pattern in an area, of a second track, which is
adjacent to a recording area of the first test pattern under a
plurality of recording conditions, the second track being adjacent
to the first track;
[0191] (c) reading the first track to detect a first read-out
signal according to each of the plurality of recording
conditions;
[0192] (d) reading the second track to detect a second read-out
signal according to each of the plurality of recording
conditions;
[0193] (e) determining an optimum recording condition for the
second track from the plurality of recording conditions and the
first and second read-out signals; and
[0194] (f) recording information in the second track under the
optimum recording condition.
[0195] As described in detail in the foregoing, the optical
recording method in accordance with a second invention is an
optical recording method of recording information on an optical
recording medium, including the steps of:
[0196] (a) recording a first test pattern in a first track on the
optical recording medium under such a predetermined recording
condition to form a wide recording mark;
[0197] (b) after the recording of the first test pattern, recording
a second test pattern in an area, of a second track, which is
adjacent to a recording area of the first test pattern under a
plurality of recording conditions, the second track being adjacent
to the first track;
[0198] (c) reading the second track to detect a second read-out
signal according to each of the plurality of recording
conditions;
[0199] (d) obtaining a second recording condition under which the
second read-out signal attains a predetermined state and performing
a calculation on the second recording condition, so as to obtain a
recording condition under which a wider recording mark is formed
than under the second recording condition and designate this
recording condition as an optimum recording condition; and
[0200] (e) recording information in the second track under the
optimum recording condition.
[0201] As described in detail in the foregoing, the optical
recording method in accordance with a third invention is an optical
recording method of recording information on an optical recording
medium, including the steps of:
[0202] (a) recording a first test pattern in a first track on the
optical recording medium under such a predetermined recording
condition to form a wide recording mark;
[0203] (b) after the recording of the first test pattern, recording
a second test pattern in an area, of a second track, which is
adjacent to a recording area of the first test pattern under a
plurality of recording conditions, the second-track being adjacent
to the first track;
[0204] (c) reading the first track to detect a first read-out
signal according to each of the plurality of recording
conditions;
[0205] (d) obtaining a first recording condition under which the
first read-out signal attains a predetermined state and performing
a calculation on the first recording condition, so as to obtain a
recording condition under which a narrower recording mark is formed
than under the first recording condition and designate this
recording condition as an optimum recording condition; and
[0206] (e) recording information in the second track under the
optimum recording condition.
[0207] As described in detail in the foregoing, the optical
recording method in accordance with a fourth invention incorporates
all the features of the optical recording method in accordance with
the first invention and is such that:
[0208] if the first read-out signal does not attain a predetermined
state, a second recording condition is obtained under which the
second read-out signal attains a predetermined state, and a
calculation is performed on the second recording condition, so as
to obtain a recording condition under which a wider recording mark
is formed than under the second recording condition and designate
this recording condition as an optimum recording condition.
[0209] As described in detail in the foregoing, the optical
recording device in accordance with a fifth invention is an optical
recording device for recording information on an optical recording
medium by at least projecting a light beam thereon, including:
[0210] recording means for recording a first test pattern in a
first track on the optical recording medium under such a
predetermined recording condition to form a wide recording mark in
determining a recording condition for a second track and also for
recording, after the recording of the first test pattern, a second
test pattern in an area, of a second track, which is adjacent to a
recording area of the first test pattern under a plurality of
recording conditions, the second track being adjacent to the first
track;
[0211] read-out means for reading the first track to detect a first
read-out signal according to each of the plurality of recording
conditions and also for reading the second track to detect a second
read-out signal according to each of the plurality of recording
conditions; and
[0212] optimum recording condition determining means for
determining an optimum recording condition for the second track
from the plurality of recording conditions and the first and second
read-out signals.
[0213] As described in detail in the foregoing, the optical
recording device in accordance with a sixth invention is an optical
recording device for recording information on an optical recording
medium by at least projecting a light beam thereon, including:
[0214] recording means for recording a first test pattern in a
first track on the optical recording medium under such a
predetermined recording condition to form a wide recording mark in
determining a recording condition for a second track and also for
recording, after the recording of the first test pattern, a second
test pattern in an area, of a second track, which is adjacent to a
recording area of the first test pattern under a plurality of
recording conditions, the second track being adjacent to the first
track;
[0215] read-out means for reading the second track to detect a
second read-out signal according to each of the plurality of
recording conditions; and
[0216] optimum recording condition determining means for obtaining
a second recording condition under which the second read-out signal
attains a predetermined state and performing a calculation on the
second recording condition, so as to obtain a recording condition
under which a wider recording mark is formed than under the second
recording condition and designate this recording condition as an
optimum recording condition.
[0217] As described in detail in the foregoing, the optical
recording device in accordance with a seventh invention
incorporates all the features of the optical recording device in
accordance with the sixth invention, and is such that:
[0218] the optimum recording condition determining means obtains a
recording condition under which an amplitude of the second read-out
signal reaches a predetermined value as a second recording
condition.
[0219] As described in detail in the foregoing, the optical
recording device in accordance with an eighth invention is an
optical recording device for recording information on an optical
recording medium by at least projecting a light beam thereon,
including:
[0220] recording means for recording a first test pattern in a
first track on the optical recording medium under such a
predetermined recording condition to form a wide recording mark in
determining a recording condition for a second track and also for
recording, after the recording of the first test pattern, a second
test pattern in an area, of a second track, which is adjacent to a
recording area of the first test pattern under a plurality of
recording conditions, the second track being adjacent to the first
track;
[0221] read-out means for reading the first track to detect a first
read-out signal according to each of the plurality of recording
conditions; and
[0222] optimum recording condition determining means for obtaining
a first recording condition under which the first read-out signal
attains a predetermined state and performing a calculation on the
first recording condition, so as to obtain a recording condition
under which a narrower recording mark is formed than under the
first recording condition and designate this recording condition as
an optimum recording condition.
[0223] As described in detail so far, the optical recording device
in accordance with a ninth invention incorporates all the features
of the optical recording device in accordance with the eighth
invention, and is such that:
[0224] the optimum recording condition determining means obtains a
recording condition under which the amplitude of the first read-out
signal reaches a predetermined value as a first recording
condition.
[0225] As described in detail so far, the optical recording device
in accordance with a tenth invention incorporates all the features
of the optical recording device in accordance with any one of the
fifth to ninth inventions, and further includes:
[0226] normalizing means for normalizing a quantity derived from
the read-out signals by the read-out means, so as to correct a
difference in sensitivity between individual tracks.
[0227] As described in detail so far, the optical recording device
in accordance with an eleventh invention incorporates all the
features of the optical recording device in accordance with any one
of the seventh to ninth inventions, and further includes:
[0228] normalizing means for normalizing a signal quantity derived
from the first or second read-out signal by the read-out means
using a maximum value of an amplitude of the first or second
read-out signal.
[0229] As described in detail so far, the optical recording device
in accordance with a twelfth invention incorporates all the
features of the optical recording device in accordance with any one
of the fifth to eleventh inventions, and further includes:
[0230] circumferential variation normalizing means for normalizing
at least either one of quantities derived from the first and second
read-out signals, so as to correct a variation in a circumferential
direction.
[0231] As described in detail so far, the optical recording device
in accordance with the thirteenth invention incorporates all the
features of the optical recording device in accordance with any one
of the seventh, ninth, and eleventh inventions, and further
includes:
[0232] circumferential variation normalizing means for causing the
read-out means to read the first track and detect a circumferential
variation normalization signal after the recording means has
recorded the first test pattern and before the recording means
records the second test pattern and for normalizing at least either
one of amplitudes of the first and second read-out signals using an
amplitude of the circumferential variation normalization
signal.
[0233] As described in detail so far, the optical recording device
in accordance with a fourteenth invention incorporates all the
features of the optical recording device in accordance with any one
of the seventh, ninth, and eleventh inventions, and further
includes:
[0234] circumferential variation normalizing means for causing the
recording means to record a third test pattern which is identical
to the first test pattern in the second track before the recording
means records the second test pattern, for causing the read-out
means to read at least either one of the first and second tracks
and to detect a circumferential variation normalization signal
before the recording means records the second test pattern, and for
normalizing at least either one of the amplitudes of the first and
second read-out signals using an amplitude of the circumferential
variation normalization signal.
[0235] As described in detail so far, the optical recording device
in accordance with fifteenth invention incorporates all the
features of the optical recording device in accordance with any one
of the fifth to fourteenth inventions, and is such that:
[0236] the first and second test patterns are constituted by a
combined pattern of marks and empty spaces, the marks and empty
spaces being longer than 2 T (T: channel bit length); and
[0237] the optical recording device further includes:
[0238] displacement correction means for correcting recording
positions of the first and second test patterns recorded by the
recording means so that marks are aligned to marks or empty spaces
along the direction perpendicular to the tracks.
[0239] As described in detail so far, the optical recording device
in accordance with a sixteenth invention incorporates all the
features of the optical recording device in accordance with the
fifteenth invention, and is such that:
[0240] the recording means records a third test pattern in the
second track before recording the second test pattern; and
[0241] the displacement correction means corrects recording
positions of the first and third test patterns so that marks are
aligned to marks or empty spaces along the direction perpendicular
to the tracks.
[0242] As described in detail so far, the optical recording device
in accordance with seventeenth invention incorporates all the
features of the optical recording device in accordance with any one
of the fifth to sixteenth inventions, and is such that:
[0243] the first and second test patterns are constituted by a
combined pattern of marks and empty spaces, the marks and empty
spaces being longer than (2+L).multidot.T, where T is a channel bit
length and L is a channel bit value required to prevent the
recording means from being adversely affected by displacement of a
recording bit when a recording condition is such that the second
test pattern can be recorded.
[0244] As described in detail so far, the optical recording device
in accordance with an eighteenth invention incorporates all the
features of the optical recording device in accordance with any one
of the fifth to seventeenth inventions, and is such that:
[0245] the first track is formed in either one of a land or a
groove; and
[0246] the second track is formed in the other.
[0247] As detailed here, in an embodiment of the optical recording
method and device in accordance with the present invention, an
optimum recording condition for a specified track is determined
through the recording of a test pattern in the specified track
under a plurality of recording conditions, based on a signal
reproduced from the specified track and a signal reproduced from an
adjacent record track.
[0248] In this embodiment, recording is actually carried out in a
specified track for which a recording condition is to be
determined. A condition under which a sufficient reproduction
signal is obtainable is determined based on a signal reproduced
from the specified track. Also, a condition under which there
occurs no cross-talk is determined based on a signal reproduced
from an adjacent track. Thus, even if there exists a difference in
recording sensitivity between adjacent tracks, a suitable recording
condition is obtainable. As a result, cross-talk between tracks
during signal reproduction and cross-erase during signal recording
in the adjacent track are restrained to minimum levels, and
recording density is improved.
[0249] In another embodiment of the optical recording method and
device in accordance with the present invention, an optimum
recording condition for a specified track is determined by
recording a test pattern in the specified track under a plurality
of recording conditions and performing a calculation on a recording
condition under which a signal reproduced from the specified track
attains a predetermined state.
[0250] In this embodiment, recording is actually carried out in a
specified track for which a recording condition is to be
determined. A condition under which a sufficient reproduction
signal is obtainable is determined based on a signal reproduced
from the specified track. Thus, even if there exists a difference
in recording sensitivity between adjacent tracks, a suitable
recording condition is obtainable. As a result, cross-talk between
tracks during signal reproduction and cross-erase during signal
recording in the adjacent track are restrained to minimum levels,
and recording density is improved.
[0251] In a further embodiment of the optical recording method and
device in accordance with the present invention, an optimum
recording condition for a specified track is determined by
recording a test pattern in the specified track under a plurality
of recording conditions and performing a calculation on a recording
condition under which a signal reproduced from an adjacent track
attains a predetermined state.
[0252] In this embodiment, recording is actually carried out in a
specified track for which a recording condition is to be
determined. A condition under which a sufficient reproduction
signal is obtainable is determined based on a signal reproduced
from an adjacent track. Thus, even if there exists a difference in
recording sensitivity between adjacent tracks, a suitable recording
condition is obtainable. As a result, cross-talk between tracks
during signal reproduction and cross-erase during signal recording
in the adjacent track are restrained to minimum levels, and
recording density is improved.
[0253] The invention being thus described, it will be obvious that
the same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be obvious to one skilled in
the art intended to be included within the scope of the following
claims.
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